This work extends the authors' earlier work on incumbency by examining, riding by riding, results in 10federal elections from 1926 to 1980. Regression results indicate that incumbency generally had a significant impact, and between 1957 and 1980 incumbency was worth about four points for the Liberals, Conservatives and New Democrats, and significantly more for the Social Credit. The results vary and seem to be smaller than those observed in Ontario provincial elections, but this may be due to the greater instability in federal politics, since general shifts in party allegiance seem to reduce incumbency effects.