This study involving 463 adolescents examined the impact of parent, teen, and parent-teen interaction processes on spontaneous disclosure to mothers. High openness in communication and stronger disclosure self-efficacy beliefs were associated with more disclosure at follow-up. Although a positive relationship was also found for maternal warmth/responsiveness when it was considered together with other parenting attributes, its unique contribution to the disclosure process was attenuated once openness and self-efficacy beliefs were taken into account. Domain-specific predictors of disclosure were also explored. Open communication was important for disclosure across all domains, while self-efficacy beliefs were critical for revealing difficult information. These findings underscore the importance of fostering an open environment in families that nurtures adolescents' confidence to engage in disclosure with parents.