To explore how students learn in community-based family physicians' offices from the student's point of view.Each student completing a community-based family medicine clerkship wrote a "critical incident" narrative about an event that was particularly educational. A coding system was developed by a multidisciplinary research team and thematic analysis was conducted.Critical education experiences were brief, problem-focused, had definitive outcomes, were often collaborative, and led to self-reflection. The most commonly identified mode of learning was "active observation." In most of these situations, the student had significant clinical responsibility, but some involved observation of complex tasks beyond the expectations of a medical student. Most (77%) identified their learning needs after having observed a preceptor, rather than prospectively. Collaboration, coaching, advocacy, and exploring affect were means whereby preceptors and students created a learning environment that students felt was safe, allowed them to recognize their own learning needs, and helped them adopt new behaviors.These findings broaden the definition of active learning to include active observation and support learner-centered and relational models of learning. Increasing preceptors' awareness of these modes of student learning will enhance the quality of education in ambulatory settings.