Using a new data source on early Canadian strikes, this paper seeks to explain the determinants of strike durations, 1901-14. Three different approaches are evaluated: a screening model, a strike-waves model, and a war-of-attrition model. The results are sensitive to strike issue. For non-wage issue strikes, the screening model performs poorly. A strike-waves model that incorporates elements of a war-of-attrition is best suited to explain the durations of multiple-issue strikes. The determinants of durations for the period are compared with findings for the period after 1945.