Using a cognitive learning theory as a conceptual base, predictions were developed as to the effects of various kinds of trainer behavior in laboratory human relations (T group) training. Data were collected by questionnaires administered to members of ten laboratory training groups, each with two trainers. Factor analysis was done on seven dimensions of trainer behavior. These dimensions were then correlated with the following criterion measures: identification with the trainer; discomfort with the trainer; group tension; group withdrawal; self perceived learning; peer-rated learning. Principal findings were: (1) "Competence" (including elements of personal security, empathy, and congruence) was a crucial trainer dimension related to member learning; identification with the trainer, and liking for the trainer; (2) Affection was positively related to liking for the trainer but not to other criteria; (3) Conditionality (tendency to reward or punish group members) was related to discomfort and to group tension but not to other criteria; (4) Conceptual Input, Openness, and Use of Influence were largely unrelated to the criteria; (5) identification with the trainer was positively related to learning, replicating the results of an earlier study. (Author/LY)