Twenty-three species of gastropod molluscs, including 10 prosobranchs and 13 opisthobranchs, were collected during a 14-month period fromZostera in the lower York River, Virginia. Salinities ranged from 16.0 to 22.4 ‰ during the sampling period; temperatures ranged from 2.8 to 28.3 C. Seasonal abundance, depth distribution, and notes on the life cycles and general ecology of this epifauna are reported.Diastoma varium andCrepidula convexa occurred throughout the year and were the two most abundant species collected.