INTRODUCTION: The Canadian population has poor and inequitable access to psychiatric care despite a steady per-capita supply of psychiatrists in most provinces. There is some quantitative evidence that practice style and characteristics vary substantially among psychiatrists. However, how this compares across jurisdictions and implications for workforce planning require further study. A qualitative exploration of psychiatrists' preferences for practice style and the practice choices that result is also lacking. The goal of this study is to inform psychiatrist workforce planning to improve access to psychiatric care by: (1) developing and evaluating comparable indicators of supply of psychiatric care across provinces, (2) analysing variations and changes in the characteristics of the psychiatrist workforce, including demographics and practice style and (3) studying psychiatrist practice choices and intentions, and the factors that lead to these choices. METHODS AND ANALYSIS: A cross-provincial mixed-methods study will be conducted in the Canadian provinces of British Columbia, Manitoba, Ontario and Nova Scotia. We will analyse linked-health administrative data within three of the four provinces to develop comparable indicators of supply and characterise psychiatric services at the regional level within provinces. We will use latent profile analysis to estimate the probability that a psychiatrist is in a particular practice style and map the geographical distribution of psychiatrist practices overlayed with measures of need for psychiatric care. We will also conduct in-depth, semistructured qualitative interviews with psychiatrists in each province to explore their preferences and practice choices and to inform workforce planning. ETHICS AND DISSEMINATION: This study was approved by Ontario Tech University Research Ethics Board (16637 and 16795) and institutions affiliated with the study team. We built a team comprising experienced researchers, psychiatrists, medical educators and policymakers in mental health services and workforce planning to disseminate knowledge that will support effective human resource policies to improve access to psychiatric care in Canada.