Nesting activity of the painted turtle (Chrysemys picta marginata) was studied for 3 yr, from 1983 through 1985, in southwestern Quebec. X-ray photography was used to determine clutch size, and radio telemetry was used to determine when and where turtles nested. The nesting seasons varied from year to year: 1983, 16 June-5 July; 1984, 9 June-28 June; 1985, 2 June-5 July. The beginning of the nesting seasons consistently correlated with the mean temperature of the previous year rather than to the mean April temperature of that same year. Distances of nests from the pond ranged from 1.1-620.5 m (x̄ = 90.4 m). The number of females exhibiting nest site fidelity increased between 1983 and 1985. Although the majority of nests were in clay, soil type seemed not to be selected. With one exception, nesting occurred in the late afternoon and early evening. When temperatures were warmer, turtles nested later in the evening. Some females did exploratory travelling before nesting, and a few remained out of the pond overnight. The duration of nesting ranged from 0.5-4.5 h. Late completion of nests was correlated with a rapid drop in temperature after the female had started nesting. Of 185 eggs known to be deposited in 1983, 45 (24%) hatchlings emerged. Predation, mostly by raccoons (Procyon lotor), accounted for 43.8% of the nest mortality in 1983; 85.7% occurred the night the eggs were deposited. An additional 25% of the nests failed due to flooding and failure of the hatchlings to emerge after hatching. Sixty percent of the intact nests had a 100% hatch. All hatchlings emerged in April and May of the following year.