With genre now viewed as a fundamental element of writing, both second language writing and mainstream composition studies have seen an increased focus on the question of how writers learn genres. The purpose of this paper is to review key findings from 60 empirical studies that have investigated this question. To this point, research has typically studied genre learning as it occurs either through professional or disciplinary practice or through classroom instruction; almost no studies have looked at the same writers as they traverse these multiple domains. I therefore categorize studies as taking place in either ‘‘practice-based’’ or ‘‘instructional’’ settings and identify trends in the research findings from each setting. After examining one study which takes place in multiple settings, I tease out some of the commonalities and distinctions between learning in practice-based and instructional contexts and between first language and second language genre learning. On the basis of this comparative review of research, I suggest future directions for the interdisciplinary study of genre learning.