Recent studies have shown that companies with relatively high debt-to-asset (leverage) ratios exhibit more variability in investment and employment patterns. Other studies argue that high aggregate corporate leverage is associated with macroeconomic instability. This paper establishes and compares the evolution of aggregate corporate leverage trends in Canada and the U.S. from 1961 to 1996. Leverage has increased nearly 50 percent in both countries, and the majority of this increase is attributable to a greater use of short-term debt instruments. Although the magnitude of the increase is similar in both countries, the period harboring the lion's share of the increase is country-specific. Most of the increase in corporate leverage in Canada occurred between 1974 to 1983; a period associated with low real interest rates and rapid capital expansion in Western Canada. The brunt of the increase in American corporate leverage occurred between 1982 and 1990. Over this period, U.S. companies were in the process of massive capital restructuring by purchasing outstanding equity with borrowed funds. This period was also associated with an increase in the number and value of U.S. leveraged buy-outs that aided in pushing financial leverage higher.