Designers' choices of methods are well known to shape project outcomes. However, questions remain about why design teams select particular methodsand how teams' decision-making strategies are influenced by project- and process-based factors. In this work, we analyze novice design teams' decision-making strategies underlying 297 selections of human-centered design methods over the course of three semester-long project-based engineering design courses. We propose a framework grounded in 100+ factors sourced from new product development literature that classifies design teams' method selection strategy as either agent-, outcome-, or process-driven, with eight further subclassifications. Coding method selections with this framework, we uncover three insights about design team method selection. First, we identify fewer outcomes-based selection strategies across all phases and innovation types. Second, we observe a shift in decision-making strategy from user-focused outcomes in earlier phases to product-based outcomes in later phases. Third, we observe that decision-making strategy produces a greater heterogeneity of method selections as compared to the class average as a whole, or project type alone. These findings provide a deeper understanding of designers' method selection behavior and have implications for effective management of design teams, development of automated design support tools to aid design teams, and curation of design method repositories, e.g., theDesignExchange.