This study reports about a yearlong study of the initiation of novice grant writers to the activity system of National Institutes of Health grant applications. It investigates the use of cognitive apprenticeship within writing classrooms and that of social apprenticeship in laboratories, programs, departments, and universities, which introduced students to the genre system of National Institutes of Health grant proposals and helped them in moving from peripheral participation to more central participation. While cognitive apprenticeship employs devices such as modeling, scaffolding, coaching, and collaboration to enhance learning in formal settings, social apprenticeship requires socialization, interaction, and collaboration with experts, colleagues, and peers in informal settings to acquire disciplinary knowledge and experiences. The study suggests that writing instructors should acknowledge and incorporate resources in other activity systems in which students participate, i.e., their laboratories and home departments, and teach genre systems rather than specific genres to better facilitate students' enculturation to activity systems of disciplinary discourse communities. (Contains 2 figures and 9 tables.)