The study compared Arab and Jewish trainees in ethnically homogeneous and heterogeneous groups, in 1 counselor training program in Israel. The 60 participants were divided into 4 conditions: Jewish trainees in homogeneous and heterogeneous groups (n = 15 in each), and Arab trainees in homogeneous and heterogeneous groups (n = 15 in each). Functioning in the group was measured through group climate (engagement, conflict, and avoidance), group intimacy, self-disclosure, and regret of disclosure. Results indicated cultural differences only on self-disclosure, with Arabs scoring lower than Jews on several dimensions. Group composition differences were mainly indicated on the climate measure, with higher scores in the heterogeneous group on conflict and avoidance, and lower scores on regret of feeling exposure. Culture-by-group interactions were found for engagement, self-disclosure, and regret after disclosure about self, with Arabs in heterogeneous groups scoring higher on the first 2 and lower on the third. These results recommend placing Arab trainees in heterogeneous groups.