School experience factors, including peer relationships, internalized behavior, and externalized behavior, have been found to influence adolescent academic motivation and postsecondary readiness. Yet, the path these critical elements take to shape postsecondary motivation and readiness remains unclear, particularly among under-researched rural contexts and populations. Thus, this study aimed to (a) examine the impact of positive rural peer relationships on academic motivation and college/career readiness, (b) examine the impact of positive rural peer relationships on internalized and externalized behavior in educational contexts, and (c) learn how both internalized and externalized behaviors might mediate the association between positive peer relationships and educational attainment factors. Two thousand sixteen survey responses from 8,541 rural adolescents (12-18 years old) from the Midwest United States were utilized to conduct a cross-sectional mediating path analysis investigating the associations between peer relationships, internalized behavior, externalized behavior, and academic motivation and college/career readiness. Results indicated that positive peer relationships are significantly associated with adolescent academic motivation and college/career readiness. A significant association between positive peer relationships, academic motivation, and college/career readiness mediated by adolescent externalized behavior and a significant association between positive peer relationships and academic motivation mediated by internalized behavior were also identified. This study advances the understanding rural peer relationships' influence on adolescent behavior and subsequent perceptions of postsecondary readiness. Implications for school practices focused on climate and culture that foster prosocial rural adolescent relationships supporting educational attainment are discussed.