This study investigated three levels of self-disclosure (public, semiprivate, private-personal) in the social penetration process. The study addressed three questions. (1) What is the nature of changes in the three levels of disclosure over time? (2) Is self-disclosure reciprocated at the three levels of intimacy? (3) Does reciprocity vary over time and, if so, how does it vary? Same-sex zero-history dyads participated in a six-week longitudinal study. The half-hour taped conversations were submitted to interaction analysis. Polynomial trend analyses and Markov analyses were used to analyze the data. The results showed: (1) a convex quadratic trend for private-personal disclosures over time; (2) reciprocity at the same level of intimacy as an interactional norm (especially at the beginning and end of the relationship); (3) a cyclical fluctuation of reciprocal interacts over time. These results were interpreted as elaborating the social penetration process.