Changes across the span of adolescence in the adolescent reward system are thought to increase the tendency to take risks. While developmental differences in decision and outcome-related reward processes have been studied extensively, existing paradigms have largely neglected to measure how different types of decisions modulate reward-related outcome processes. We modified an existing decision-making paradigm (the Stoplight Task; Chein et al., 2011) to create a flexible laboratory measure of decision-making and outcome processing, including the ability to assess modulatory effects of safe versus risky decisions on reward-related outcome processes: the Yellow Light Game (YLG). We administered the YLG in the MRI scanner to 81 adolescents, ages 11–17 years, recruited from the community. Results showed that nucleus accumbens activation was enhanced for (1) risky>safe decisions, (2) positive>negative outcomes, and (3) outcomes following safe decisions compared to outcomes following risky decisions, regardless of whether these outcomes were positive or negative. Outcomes following risky decisions (compared to outcomes following safe decisions) were associated with enhanced activity in cortical midline structures. Furthermore, while there were no developmental differences in risk-taking behavior, more pubertally mature adolescents showed enhanced nucleus accumbens activation during positive>negative outcomes. These findings suggest that outcome processing is modulated by the types of decisions made by adolescents and highlight the importance of investigating processes involved in safe as well as risky decisions to better understand the adolescent tendency to take risks.