A study was made to compare the effectiveness (determined by individual behavior change) of three sensitivity training conditions--spaced, massed, and combined--compared with each other and with a control group (no training); and to determine the relationship between 25 personal characteristics and the behavior change under the various conditions of training. Four or five behavioral areas were selected and an individualized Behavior Change Rating Sheet constructed. Spaced groups met for 30 hours spaced over 10 weeks; massed groups met for 24 hours in one continuous session; and combined groups met for a weekend with about 10 hours of training, five weekly two-hour sessions, and a final weekend. Ratings were made by each participant of his own change and also by outsiders at the end of the sessions; after three months, similar ratings were made by each participant and two outsiders. All experimental group participants showed more positive change just after training than control groups; after three months, the spaced and combined groups continued to show more behavior change but the massed group did not differ from the control group. Experimental groups did not differ significantly from each other; however, there were trends in the data. (EB)