This study took a life course approach to examine associations among family income from birth to age 15, and adolescent health and well-being. Utilizing latent growth mixture modeling, we identified four distinct family income trajectories based on changes in low-income status (family income [less than or equal to] 200% of the federal poverty line) over 15 years, which in turn related to their outcomes in adolescence. More specifically, youth living in a consistent state of higher income from birth to age 15 ("Consistent Higher Income") reported better health and behavioral outcomes than youth in the "Consistent Low Income," "Increasing Income," or "Decreasing Income" groups. Furthermore, despite tending to have relatively high-income levels at the beginning of life, the "Decreasing Income" group showed several risky behavioral and health patterns, including more sexual risk-taking and high blood pressure. Results underscore the importance of studying changes in family income across childhood and adolescence.