Background: Professional skills are critical in engineering practice. Differing definitions and lack of empirical evidence make it difficult to help students develop these skills. Purpose: This research seeks to understand what it means to have professional skills in an industrially situated capstone project and, by extension, in engineering. We also aim to demonstrate the influence on those skills of the feedback provided to students. Design/Method: Our ethnographic study employs discourse analysis to focus on professional skills. Using the construct of communities of practice, we describe and analyze conversations between a coach and four student teams as the coach provided feedback, and conversations among students as they worked in teams. Results: Approximately half the discussion addressed the following professional skills: communication, documentation, teamwork, the economic impact of engineering solutions, and project management. Development of professional skills promotes students' enculturation into both a disciplinary community (chemical engineering) and an industrial community (semiconductor industry). Feedback on professional skills generally was given in the context of technical aspects, and we found an interplay between the teams' participation in professional skills activities and participation in more technical activities. Conclusions: Participation in engineering design projects provides students opportunities to practice both professional and technical skills. Feedback on professional skills helps students recognize how to simultaneously represent themselves as legitimate members of multiple communities of practice.