We explore and critically reflect on the research development of eight science or engineering doctoral students serving as research assistants over the course of an academic year. We use a cognitive apprenticeship framework, assumed to explain doctoral students' skill development, to interpret narratives of skill development for students and their faculty supervisors, and compare these narratives against empirical measurements of student research skill development over the course of an academic year. We found abundant evidence for the "cognitive" component of cognitive apprenticeship, but questionable evidence for the "apprenticeship" component. We suggest that cognitive apprenticeship can be particularly potent in the development of students' research skills through research assistantship, but not without deliberate intention of both faculty supervisor and student.