Self-directed learning is a key competency in life-long learning, an outcome often cited for engineering education, and is dependent on students' motivation, meta-cognition, and self-regulation with regards to a learning task. Few studies have addressed the aspects of engineering learning environments that promote the development of self-directed learning abilities. The goal of this study was to identify relationships between students' perceptions of their self-directed learning ability and their learning motivation within a project-based learning environment. Junior engineering students in a test cohort with heavy emphasis on project-based learning completed surveys on self-directed learning aptitude and learning motivation. Responses were compared with a quasi-control group of junior students in traditional learning environments. Results show that the test cohort scored significantly higher on two types of motivation (intrinsic and identified regulation) that correlated strongly with students' use of self-regulated learning strategies.