Background: For vocational and professional education to remain relevant, instructors need to keep developing themselves and their practices. Much of instructor learning happens on-the-job. Drawing on literature on teacher learning in the workplace, this article explores how structural and cultural conditions shape professional learning of instructors in departments for post-secondary vocational and professional education in western Canada. Methods: A multiple case study approach was used to explore how instructors perceive departmental conditions as enhancing or inhibiting professional learning. Interview data, meeting observations, and program documentation was collected from 27 instructors from 5 departments in three institutes for post-secondary vocational and professional education. The educational programming in the five departments cover four industry sectors: two healthcare departments, one building trades, one business, and one social services department. Results: Structural conditions reported to facilitate instructor professional learning at the department level include student feedback, job-rotation, coordinating work-placements, and whether participation in continuing professional development is a licensing requirement of the profession. Heavy workload and the way teaching is scheduled are most often reported as conditions inhibiting learning. Considering cultural conditions, three in-depth case descriptions illustrate how instructors draw on beliefs and practices prevalent in their original trade/profession when shaping their departmental culture as a learning environment. Conclusions: The concept of sense-making proved useful to describe how instructors draw on elements of the occupational culture taught in the program when shaping their workplace as a learning environment. This influence of occupational culture could help explain previously observed differences in how instructors from various industry sectors engage in professional learning. Organizational support is warranted for facilitating organizational conditions for instructor learning including the development of departmental leaders' capacity to influence workplace conditions for professional learning.