To prepare students for the future workforce, it is important to provide them with knowledge and guidance about professional software engineering practices. One critical element of workplace practices is learning on the job. There are few studies of how software engineers learn on the job and little focus within the literature on how this understanding can help train students. In this paper, we present a qualitative interview-based field study of workplace learning among professional software engineers. We conducted in-depth interviews with ten software engineers and analyzed the data using thematic analysis based on the learning ecologies framework. In our findings, we identify and discuss professionals’ motivation and reasons for learning, the different resources they use to learn, the challenges they face in their learning, and their views on the relationship between formal education and on the job learning. We draw implications of the findings for teaching and learning, and future research.