Theoretical formulations concerning the relationship of nonverbal behavior to the social penetration processes, i.e., the development of interpersonal relations (Altman & Taylor, 1973) were examined via acted, videotaped conversations in which subjects role played good friends (GF) or casual acquaintances (CA) discussing intimate (I) or nonintimate (NI) topics. The methodological approach adopted for this study was unique in three ways. First, patterns of nonverbal behavior rather than single behaviors were the primary units of analysis. Second, data were collected during dynamic, ongoing conversations rather than from static poses or photographs. Finally, the use of a repeated measures design permitted evaluation of the importance of individual differences. Pattern analyses generally confirmed predictions: the GF by NI cell was characterized by nonverbal behavior patterns indicative of relaxation, while tense behavior patterns occurred in the CA by I cell.