As they think about their future, high school students can face a wide range of education and career choices. How do they choose? Who helps young people make their educational and career choices? In particular, to what extent do schools help students with these decisions? Given the importance of education and career decisions for life success, these are not idle questions. A significant amount of research has been done on this topic, most of which has been conducted within the framework of "social cognitive career theory" (SCCT). SCCT focuses on individuals' internal, cognitive processes (e.g., achievement, expectations) and how those cognitions interact with external, contextual factors (e.g., social supports and barriers) to influence career decisions and development. This Brief uses data from the High School Longitudinal Study of 2009 (HSLS:09) to explore the less well-developed area of relative influences in students' decisionmaking by quantitatively examining multiple sources of influence on students' thinking about two major life decisions: their future education and their career choices. As discussed in this brief, the HSLS:09 data allow for an examination of who students believe most influences their thinking in each domain and for a comparison of influences across the two domains. The data also enable an examination of whether students' reports on who has the most influence in each domain vary by students' socioeconomic status (SES). This Brief provides a relatively simple descriptive analysis, excluding other potential factors that research has shown influence students' decisions in combination with or in addition to the factors examined, such as students' post-high school intentions and race/ethnicity (e.g., Fouad and Byars-Winston 2005; Lent, Brown, and Hackett 1994). As with any correlational study, the reader should not infer causation from simple relationships.