We monitored six flocks and five active nests of the Plush-crested Jay (Cyanocorax chrysops) at three sites in the Atlantic Forest in southern Brazil. The sites had different vegetation compositions and spanned different levels of anthropogenic disturbance. Home range size in fall/winter was 20–30 ha and the breeding territory size in spring/summer was 5–10 ha in size. Territories were smaller across sites with higher anthropogenic food supplementation. Flock sizes were 5–11 individuals during spring/summer and 8–15 individuals during fall/winter. The Plush-crested Jay is a cooperative breeder, nests were 4–7 m above ground level, the incubation period was 18-20 days, brood size (x¯ ± SD) was 3.4 ± 0.80 eggs per nest, and nestlings fledged 23 ± 1.26 days after hatching. This species occupies all forest strata but tends to use the understory and middle levels most (G  =  178.2; P < 0.01). Invertebrates were the most frequently consumed item in all areas, but percent consumption varied among sites (G  =  105.06; P < 0.01). We observed 110 food caching events throughout the year, primarily seeds of Araucaria angustifolia, maize, and coconuts. Caches were on the ground (n  =  40), in epiphytes (n  =  47), and on branches (n  =  23). Levels of anthropogenic food supplementation resulted in variation in territory and home-range size, nestling survival rates, strata occupation, and diet composition of the Plush-crested Jay.