This article presents insights from a study into instructor professional learning in vocational and professional education (VPE) in Canada. While most studies on instructor learning focus on learning through formal professional development programmes, this study specifically focuses on professional learning as it happens in day-to-day practice. Analysis of 116 learning episodes reported by 27 instructors from various institutes for VPE shows that instructor learning is mainly focused on developing pedagogical content knowledge (PCK). Learning episodes studied were often externally prompted, not self-directed and involved mostly action-oriented reflection. Ellström's theory of adaptive and developmental learning is used to further explain these findings. Because of the specialized nature of the content taught in VPE programmes, formal training in PCK is often not available; instructors rely on trial and error, student feedback and peer feedback to develop PCK. Educational leaders within institutes for VPE should consider encouraging professional development models that include collegial dialogue, such as mentoring and communities of practice, as well as the implementation and enactment of professional learning plans. Further research could focus on how existing workplace practices may be enhanced to further support instructor professional learning.