Recommendation letters play important roles in evaluating candidates for college and graduate school admission, postdoctoral and other fellowships, employment, awards, and other opportunities and recognitions. Yet students and others generally receive little guidance on how and when to approach potential recommenders and what information and materials to give them. Likewise, although faculty members and others in the sciences often are asked to write recommendation letters, few have received guidance on how to do so effectively and efficiently. This workshop will provide advice on both requesting and writing recommendation letters, in order to facilitate provision of recommendation letter that work but do not entail too much work.