The number of workers who hold more than one job (a.k.a. multiple jobholders) has increased recently in Canada. While this seems to echo the view that non-standard work arrangements are becoming pervasive, the increase has in fact been trivial compared with the long-run rise of multiple jobholding that has occurred since the mid-1970s. In this paper, we document this historical evolution and provide a comprehensive account of its underlying dynamics. To this end, we use restricted-access panel micro-data from the Canadian Labour Force Survey to construct transition probabilities into and out of multiple jobholding. We analyze these data through the lens of a trend decomposition that separates out the role of labor market inflows and outflows. The picture that emerges from our analysis is one of continued increases in the propensity of workers to take on second jobs. We argue that changes in technology and in preferences could both be responsible for this evolution.