This study investigated how secrets unfold over the course of therapy in a naturalistic setting, including identifying longitudinal patterns and investigating relationships with other session-level variables. Participants were 39 client and graduate student therapist dyads in open-ended therapy at a community psychotherapy clinic. Data on concealment, disclosure, working alliance, real relationship, and session evaluation were collected after each session. Data were analyzed using Hierarchical Linear Modeling (HLM). Results demonstrated that disclosure and concealment of secrets are relatively infrequent occurrences, with disclosure occurring more often than concealment. Over time, clients became less likely to disclose a secret and less likely to conceal a significant secret. Clients rated the working alliance as lower for sessions where secrets were disclosed, but this relationship was less pronounced when the disclosed secret was viewed as significant. Clients rated session quality as higher for sessions in which they both concealed and disclosed secrets, as well as for sessions in which a preoccupying secret was shared. Clients tended to feel neutral or positive about their disclosures and believe that the disclosure had no change on how they were viewed by their therapist. Implications for practice and research are discussed.