Homicide rates in Canada have shown a decline since 1975, but there has been little empirical study of this trend. P. Holinger (1987) predicted and confirmed that the size of the cohort aged 15-24 in the United States population was associated with the rise and fall of the homicide rate in that country. This study was designed to test this hypothesis in Canada. The results show, even if one controls for other socio-economic variables, the most significant prediction of the decline was, indeed, the proportion of the youth population.