The spider fauna of vineyards in northern parts of North America are completely unknown, even though spiders represent important natural enemies to phytophagous insects occurring in vineyards. Weekly pitfall trapping in 1998 and 1999 in two vineyards in southern Quebec yielded over 4,600 spiders belonging to 97 species and 16 families. Spider assemblages (diversity and community composition) were similar between the two vineyards independent of environmental differences. However, some species-specific patterns were noted when the two vineyards were compared. High landscape diversity, including fallow fields and adjacent apple orchards, is hypothesized to account for a higher abundance of certain agrobiont species in one of the vineyards. Phenological data shows the most abundant linyphiid species, Tennesseellum formicum (Emerton), exhibits high phenotypic variation, and its multivoltine life cycles may be of adaptive importance for vineyards that are frequently disturbed. We also note several other species exhibiting period of peak activity in the spring [e.g., the wolf spiders Pardosa moesta Banks and Trochosa ruricola (De Geer)] or autumn [e.g., the funnel-web spider Agelenopsis potteri (Blackwall)]. Species turnover was high between sample dates, and data on activity and species richness of two guilds (web-building spiders and hunting spiders) indicate that many species that differ in foraging mode are active during all months of the growing season. The diverse ground-dwelling spider fauna in vineyards is therefore well positioned to prey on phyotophagous pests, and their populations should be conserved in these agroecosystems.