When he arrived at the Institute, Wolf was assigned to teach the teachers of the four preschools a course in learning principles. The four class projects designed by Wolf and carried out by the teachers constituted the original experimental documentations—the discovery—of the reinforcing power of adults' social attention for children. We had never seen nor imagined such power! The speed and magnitude of the effects on children's behavior in the real world of simple adjustments of something so ubiquitous as adult attention were astounding. Those four studies were subsequently published (Allen, Hart, Buell, Harris, & Wolf, 1964; Harris, Johnston, Kelly, & Wolf, 1964; Hart, Allen, Buell, Harris, & Wolf, 1964; Johnston, Kelly, Harris, & Wolf, 1966), and one of them, titled “Effects of Social Reinforcement on Isolate Behavior of a Preschool Child,” became Wolf's first citation classic (i.e., identified as one of the most frequently cited publications by Current Contents: Social & Behavioral Sciences). Forty years later, social reinforcement (positive attention, praise, “catching them being good”) has become the core of most American advice and training for parents and teachers—making this arguably the most influential discovery of modern psychology.

The research methods that Wolf pioneered in these studies were also groundbreaking: direct observation with interval recording and interobserver reliability, systematic alteration of the natural environment, reversal and multiple baseline single-subject experimental designs. These occurred at a time when, with the exception of Ayllon's work, the only real-time data of human behavior were from laboratory settings, and the few real-world efforts were being documented only with field notes. Precedents for the structured observations were found in several early child psychology studies, and precedents for field interventions were common to all teaching and helping professions, but the research designs were new to psychology. These designs did not come from conventional experimental design logic, which required experimental and control groups to show causality. Nor did they come from the conventions of the experimental analysis of behavior, which relied on multiply revisited steady states of behavior associated with different conditions to show causality. The reversal or ABAB design that Wolf reinvented from Claude Bernard's early examples in experimental medicine entailed establishing a baseline of repeated quantified observations sufficient to see a trend and forecast that trend into the near future (A); to then alter conditions and see if the repeated observations become different than they were forecast to be (B); to then change back and see if the repeated observations return to confirm the original forecast (A); and, finally, to reintroduce the altered conditions and see if the repeated observations again become different than forecast (B). (The unprecedented multiple baseline design that Wolf first demonstrated at this time, and later elaborated on with other colleagues, similarly entailed concurrently establishing baselines of repeated observations of either more than one behavior, more than one condition, or more than one person sufficient to see trends in each baseline and forecast those trends into the near future; to then alter conditions for one baseline and see if the repeated observations of that baseline become different than they were forecast to be, and that the other baselines remain as forecast; to then similarly alter conditions for a second baseline and see if it too becomes different than forecast while the remaining baselines confirm their original forecasts; and so on.) Wolf reinvented these methods to fit the problems being studied: how to show that this beneficial intervention with this child caused a quantifiable change in that behavior. In these four preschool studies, Wolf first assembled field observation, field intervention, and single-subject design into a field research methodology. That methodology came to define applied behavior analysis.

Among Wolf's other duties at the Institute of Child Development was the task of building, at a rural institution, an experimental classroom for children with developmental disabilities. He had brought from Arizona State the first seed of an extrinsic reinforcer methodology that he now cultivated into a powerful motivational system—now called a token economy or point system—that could spread out the powerful reinforcing properties of “big things” into many small physical tokens or recorded points that could be accumulated to buy them. And just as important, Wolf had noted that the process also artificially reordered the social attention of those who dispensed the tokens or points by necessarily increasing their attention to the positive behaviors they were rewarding. He designed a token system for the classroom, and revised it until it was easy to run and successfully sustained high rates of academic behavior (and the children made steady progress through the reading, writing, and arithmetic programmed instruction curricula that Birnbrauer, Bijou, Wolf and others were developing) (Birnbrauer, Bijou, Wolf, & Kidder, 1965; Birnbrauer, Wolf, Kidder, & Tague, 1965). With teachers in another classroom in that institution, Wolf also provided the first example of a functional analysis of a severe problem behavior with a field experiment demonstrating that the frequent vomiting by a student was, surprisingly, operant behavior maintained by its function of returning her to her dormitory (Wolf, Birnbrauer, Lawler, & Williams, 1970; Wolf, Birnbrauer, Williams, & Lawler, 1965). Wolf's values, and his intervention strategies, were always about energizing people with positive reinforcement and building their skills and capabilities, and about paying increased attention to the positive things that people do. After he had pioneered the point system or token economy invention into a reliable social technology in the classroom, he relied on it as a part of his subsequent problem-solving research and development because it could sustain such high effort and enthusiasm for learning and practice.

At the same time, Wolf accepted the challenge of getting Dicky, a post-cataract-surgery 3-year-old boy with autism who displayed temper tantrums and self-injury and who resided in a psychiatric hospital 50 miles distant, to wear glasses. Thus began a year of weekly drives that culminated in the premier study of behavior modification. Wolf had to develop techniques to deal with Dicky's tantrums and sleeping and eating problems, and to establish wearing glasses, basic socialization, and functional speech. After having just discovered the power of adult attention for young children, and realizing that the staff could not simply ignore temper tantrums, especially violent ones with mild self-abuse, Wolf decided to prescribe a response to tantrums that would minimize any social reinforcing effect of the necessary attention and counterbalance that reinforcement with a period of social isolation. The prescription for tantrums was to place Dicky, calmly and without comment, in his room until the tantrum ceased and at least 10 min had passed. When tantrums were under control and after wearing glasses had been hand shaped, Dicky began to throw his glasses occasionally. When the social isolation prescription was applied, glasses throwing decreased from about twice per day to zero. But the hospital staff doubted that it was due to the procedure because Dicky didn't seem to mind being taken to his room; he just rocked in his rocking chair and hummed to himself. Because throwing glasses was both less serious and more reliably measured than tantrums, Wolf agreed to discontinue the procedure—and glasses throwing soon increased to the previous level. The social isolation procedure was reinstated, and glasses throwing decreased again to zero. When writing the paper about the study, Wolf wanted to emphasize the applicability of operant conditioning “microteaching” techniques to children with severe disabilities. The social isolation procedure had no precise analogue in operant conditioning, but the practice of briefly turning out the lights after errors in match-to-sample research with pigeons (to avoid reinforcing error–error–correct sequences) had been called time-out. So, in the paper, Wolf decided to attach that label to contingent social isolation for children's acts that could not be ignored. Thus, this nonviolent alternative to physical punishment—based on his discovery of the power of adult attention for children—was labeled time-out in the paper that first introduced the procedure and documented its effectiveness. Forty years later, it is now recommended by the American Academy of Pediatrics (1998), and most of the parents (and teachers) in America—at the moments when their parents would have spanked or slapped—use social isolation instead, and call it time-out. Time-out is now a part of our general culture in everyday talk and popular cartoons, and is arguably the most widely adopted social invention of modern psychology.

That study with Dicky and three follow-up studies are also noteworthy for discovering how operant conditioning techniques could be applied to shape verbal imitation and meaningful speech in children with severe disabilities in the now familiar discrete-trials approach (Risley & Wolf, 1964, 1967; Wolf, Risley, Johnston, Harris, & Allen, 1967; Wolf, Risley, & Mees, 1964). These studies, which also included shaping social skills and toilet training together with Wolf's functional assessment of vomiting, started a movement in behavioral psychology to apply operant conditioning microanalysis and microteaching techniques to behavior problems of people with severe disabilities, culminating in a new profession: the board-certified behavior analyst. In this and subsequent work, Wolf's emphasis on the entirety of a person's daily life—analyzing consequences, building skills, motivating effort and enthusiasm—and on social validity also led to a related movement in education called positive behavior support and to the requirements for functional assessments in current federal law. The initial article reporting the work with Dicky, titled “Application of Operant Conditioning Procedures to the Behaviour Problems of an Autistic Child,” became Wolf's second citation classic.

After accomplishing all this in 28 months at Bijou's institute, in 1964 Wolf took a regular academic position at the University of Arizona, where among other things he completed the first systematic demonstration of the use of operant techniques to toilet train people with severe developmental disabilities (Giles & Wolf, 1966). In 1965 Wolf was recruited to the University of Kansas where he spent the rest of his professional life. Mont Wolf came to Kansas because of the opportunity to create solutions for problems of segregation and poverty on a community-sized scale at the Juniper Gardens Children's Project. He came because of the research administration vision and funding genius of Richard Schiefelbusch, who could temporarily support him and his students and colleagues (and who could teach us all how to fund our problem-solving research). He came because Baer had convinced Frances Horowitz to allow us to create, in the new Department of Human Development that she headed, a PhD program that emphasized immersion in research, demonstrated mastery of professional competence, but few required courses. Many former students and former colleagues also came to Kansas as soon as we could, to continue the excitement of collaborating with Wolf and sharing his vision of a new field of problem-solving research.

Wolf then put in 3 years of heroic effort on top of his research projects and student mentoring to create a field out of a journal. To appreciate the abysmal state of the articles submitted, one needs to go back to the edited books of readings in behavior modification or therapy in the late 1960s (e.g., Bijou & Baer, 1967; Ullmann & Krasner, 1965; Ulrich, Stachnik, & Mabry, 1966) before JABA began to serve its function of providing models and reinforcement for field research with reliable measurement and valid design. Wolf was an unnamed coauthor of half the articles in the first two volumes as he helped authors reanalyze and rewrite their reports to salvage any parts of any work in which measurement and design allowed even tentative conclusions. He also “educated by review”: Everyone who submitted an article was assigned someone else's article to review. He gave extensive feedback to everyone—authors and reviewers—and circulated reviews to everyone who needed a better example, and edited offensive statements out of the comments of inexperienced reviewers. His expressed goal was that everyone who submitted a paper, whether it was accepted or rejected for publication, would submit another paper, and that paper would be a better one. Wolf was successful. Within 2 years, submissions of good research increased as people began to do field experiments with adequate measures and single-subject designs because the outlet for such research existed, because early articles had provided them with good examples of it, and because they received encouragement and instruction more than criticism with each submission. An overview instructional article that Wolf and others wrote for JABA's first issue also helped (Baer, Wolf, & Risley, 1968). That article, titled “Some Current Dimensions of Applied Behavior Analysis,” became Wolf's fourth citation classic. In fact, for several years it was the most frequently cited article in the social sciences, partly because it contained the first discussion of Wolf's single-subject research designs.

As the number of homes grew and additional training sites were established and the model was adapted to serve other kinds of children and youth, Wolf designed a new professional organization, The Teaching-Family Association, as a durable, decentralized vehicle for supporting high-quality delivery of the Teaching-Family Model. An estimated 10,000 teaching parents, treatment foster parents, home-based therapists, independent living counselors, and others—who have served over 85,000 children, youth, and dependent adults—have been trained and certified since the association was established. In 1975,Wolf also took the Teaching-Family Model, by then roughly complete, to Father Flanagan's Boys Town. Their on-campus program was converted from dormitories to family homes with live-in teaching parents. The model then became the foundation for Girls and Boys Town's far-reaching residential and foster family programs that have served 40,847 troubled or at-risk girls and boys since 1975. In 1996, Wolf received the Father Flanagan Award for Service to Youth in recognition of his 30 years of mission-oriented research, the comprehensiveness of the resulting solution, and the astounding number of identifiable people measurably benefited by the Teaching-Family Model. Wolf's illness prevented him from mounting his planned teaching campaign to behavioral psychology about what he had learned about mission-oriented research and building complete solutions to societal problems. But in the middle of his decline, a group of his collaborators in the development of the Teaching-Family Model helped him to write a brief retrospective account of the model's development (Wolf, Kirigin, Fixsen, Blasé, & Braukmann, 1995). That account references the research demonstrations of dozens of pieces of the Teaching-Family Model and the model's outcomes in many of its applications.

Montrose Wolf led by example, by enthusiasm, by patient instruction, not by exhortation. He did not have to be in charge to accomplish his ends—collaboration was his method, and he was its master. And we collaborators always got more than we gave. Several different people were heavily involved in each of his many contributions described above (only his social validity paper was an isolated act). In retrospect, in our work with him we collaborators were actually mostly eager followers—we either did something that he recognized as useful, tried something he suggested, or wrote the draft he outlined—but his recognitions, suggestions, and outlines always occurred in exciting brainstorming discussions that made each of his collaborators a full partner of that part of Wolf's larger vision. Although he was a truly humble person, Wolf accepted second or last authorship on most of the published products of his vision and ingenuity as a practical way to motivate his collaborators. His goal was to make a dent in our society's problem-solving ineptness, not to make a splash for recognition. Wolf insisted that meaningful discoveries, inventions, and solutions in human affairs can only be developed by teams of people working together on ambitious projects over long periods of time. He was certain that collaboration was a habit that could be taught through practice, and he organized all his classes and research meetings accordingly. Ninety-six different people coauthored one or more publications with him. For most collaborators, working with Wolf was the most productive season of their careers. For all collaborators, working with Wolf was the most exciting time of our lives.

Because of Huntington's disease, Wolf was unable to assume the expected later career role of a senior statesman in behavioral psychology. After about 1985, he conserved his steadily diminishing energy and brilliance to try to complete the Teaching-Family example of mission-oriented research. He never ran for elective office in professional organizations. His few offices and committee memberships were mostly honorific. He avoided further editorial or professional review responsibilities. Because of this, psychology was denied the mid- and late-career leadership of one of its most influential figures.

Montrose Wolf's vision of an experimenting society was influenced by Francis Bacon and B. F. Skinner, and later by Donald Campbell and Richard Schiefelbusch. His research methods were influenced by his belief in active problem solving, and he therefore followed Claude Bernard's dictum of experimental medicine: When you have to try to help, the experimental question then becomes “What would have happened had you done nothing?” If we consider Wolf's professional contributions in that light, the productivity of the hundreds of his collaborators and students, the functioning of thousands of participants in his several projects, the knowledge bases of those project areas, the practices of behavioral psychology, the field of applied behavior analysis, the discipline of psychology, and the problem-solving abilities of our society would have been notably less without him.