To explore the relationship between need-supportive advising and students' decision making on academic majors, we conducted a longitudinal study of 145 students based on their reports of basic psychological need satisfaction and their decision-making processes. We hypothesized that need-supportive advising would positively contribute to autonomous and competent decision making. Results suggest that students who receive need-supportive advising at the beginning of the academic year report increased feelings of autonomy and competence about choosing a major toward the end of the year, implying that advising satisfies students' basic psychological needs throughout the year. Implications and future directions are discussed.