Although prior research suggests that ER development typically exhibits a positive growth trajectory across adolescence as prefrontal brain regions continue to mature, individual differences in the rate of development have yet to be fully elucidated. The present study illustrates developmental processes in which family context (i.e., socioeconomic status, parent perceived stress, and family emotional climate) influences developmental trajectories of emotion regulation using both growth curve and latent change score analyses. The sample included 167 adolescents (53% males) who were first recruited at age 13 or 14 years and assessed annually four times. Our results support the mediating role of family emotional climate in the association between socioeconomic status and changes in emotion regulation, but not parent perceived stress. Our findings emphasize the constraints placed on ER development as a result of low SES and highlight the need for intervention efforts at proximal levels, such as the family emotional climate, for adolescents who face such distal risk factors. / M.S. / Given continued brain development across the period of adolescence and maturation in specific brain regions related to emotion regulation (the ability to change the experience or expression of an emotion), we expected that emotion regulation abilities would also continue to develop during this period. We were also interested in understanding what family contextual factors may be influencing how emotion regulation develops. For example, we expected that family economic and social position (including education level, income, aid, and satisfaction with finances), parent stress, and the family emotional climate (the degree of both positive and negative emotionality expressed within the family unit through parenting practices and the quality of the parent child relationship) would affect how emotion regulation unfolds in adolescents. That is, we predicted that families demonstrating a higher socioeconomic status, less parental stress, and better parenting practices would create safe and supportive contexts to learn and practice emotion regulation skills, resulting in adolescents with more adaptive emotion regulation abilities. We tested our hypotheses using longitudinal analyses from 167 adolescent participants and their parents. Our results demonstrate that parent stress is not directly related to emotion regulation development, but that socioeconomic status is related to emotion regulation development through family emotional climate. Such results suggest that for adolescents who may be at risk for developing poor emotion regulation abilities, their family can be taught skills related to improving parenting and the quality of the relationship between parent and adolescent in order to lessen the possibility of that outcome.