While the majority of workplace learning is informal, most organizational resources devoted to learning are allocated to more formal means, such as training. The purpose of this study was to investigate how instructional designers facilitate informal learning in the workplace. Three hundred eighty-five practitioners completed an online survey developed to measure how informal workplace learning is facilitated. In addition, 20 survey respondents participated in follow-up interviews. Findings revealed that practitioners employ a variety of methods to facilitate informal workplace learning. Sharing knowledge, materials, and resources emerged as the most common approach. As proponents of learning, instructional designers, as well as their managers and clients, may leverage the findings of this study to facilitate informal workplace learning, thus increasing performance.