Despite intense interest in informal learning in the workplace, few attempts have been made to synthesize the current literature. This article provides an integrative and analytical review of prior empirical studies with two research questions: (1) How has informal learning been conceptualized and measured in prior research? and (2) What factors influencing informal learning in the workplace have been empirically identified? Based on the findings from the first research question, the authors propose a conceptual framework for understanding informal learning activities using three dimensions: learning competence, intentionality, and developmental relatedness. To answer the second question, Lewin’s field theory, which captures the importance of the person and the environment fit, was applied to identify antecedents of informal learning at the individual, group, and organizational levels. The authors then provide a critique of the state of the informal learning literature and outline targeted suggestions to guide practice and future empirical, theoretical work.