Turfgrass lawns support a diverse fauna of arthropods including ground beetles, a major predator and seed feeding group. Despite their ubiquity and ecological roles, few studies have looked at ground beetle diversity and composition within lawns. We studied assemblages of Carabidae and their seasonal abundance in a newly established and a 10-yr-old lawn located in Quebec City, Canada. Carabids were sampled from May to November in 2003, 2004, and 2005 using pitfall traps. A total of 17 species in 10 genera and 7 tribes were identified. In the new lawn, three ground beetle species represented 72% of total Carabidae: Harpalus rufipes (30%), Clivina fossor (30%), and Amara aenea (12%). In the older lawn, the most abundant species were Amara aenea (31%), Bembidion mimus (21%), and Dyschirius brevispinus (19%), representing 71% of total Carabidae. Ground beetles were six times more abundant at the older site, and there were minor differences in species diversity between sites and years. For the most abundant Carabidae collected, seasonal abundance patterns were similar for A. aenea and B. mimus with peak abundance in July and/or August. For Harpalus rufipes, seasonal abundance was higher in 2003 and 2005 than in 2004, suggesting a biennial life cycle.