He worked as a professor at Indiana University for 34 years, where he conducted numerous projects examining basic behavioral processes, especially discrimination learning in the area of negative reinforcement. In general, Dinsmoor's work was influential in the development of scientific knowledge on stimulus control. His work allowed for the formation of a narrative on the differential effects of various types of stimulus control techniques on differing behaviors. James Dinsmoor worked with apparatuses that provided reinforcers (e.g., food) and punishers (e.g., electric shock) to laboratory animals. He knew how to build this equipment himself, and often insisted that his graduate students learn to do the same. James Dinsmoor was also heavily involved in scholarly communities through his role as an experimental psychologist. He served in a leadership role in a number of psychological institutions, such as the Midwestern Psychological Association (President and Secretary-Treasurer), Division 25 (behavior analysis division) of the American Psychological Association (multiple positions), and the Society for the Experimental Analysis of Behavior (President and Chairman of the Board). Early in his career, he helped organize the creation of the Journal of the Experimental Analysis of Behavior, which is still in circulation today. In addition to his work as an experimental psychologist, James Dinsmoor was involved politically. In the 1960s, he was involved in activism against the Vietnam War through his university, and he spoke openly at campus rallies and on the radio about his opposition to the war. He was once arrested (but subsequently acquitted) at a war protest in the 1960s. In 1966, he ran for Congress on a platform of opposition to the Vietnam War. Timberlake quoted James Dinsmoor's campaign flyer as stating:  "”The time has come for plain speaking. More than two hundred thousand young Americans have been taken from their homes, their jobs, and their families to fight and to die in a distant land. Our rate of casualties is rapidly approaching twenty-five to thirty thousand a year. Our young men are being trained to destroy crops, to burn entire villages, and to kill. In many cases, they cannot distinguish between enemies and friends, between armed guerrillas and innocent civilians.” "  Dinsmoor did not win the seat at Congress. Instead, he continued his academic work in the field of behaviorism. Although he was retired in 1986, James Dinsmoor continued to conduct experiments, publishing as many as 20 articles after his retirement (see Bibliography, below), including one article published the year before his death.