Between October 1987 and December 1988, 732 winter flounderPleuronectes americanus, 91–380 mm total length, were collected during biweekly sampling from Narragansett Bay, Rhode Island. Left sagittal otoliths from these fish were embedded in epoxy resin, and transverse sections through the foci were prepared. With hyaline zones considered as annual increments, ages ranged from 1 to 11 for 608 winter flounder; 97% of the fish were younger than age 5. The dorsoventral otolith diameter was determined by linear regression analyses to be the best (r2= 0.90) of six “radial” axes for increment measurements. Marginal increment analyses for ages 1–4 showed that the increments, each composed of one opaque and one hyaline zone, are deposited annually, which clearly verified sectioned otolith ages for age-2 and age-3 fish. Opaque edges were prevalent in May, June, and July. Sectioned otoliths from winter flounder can provide clear increments and measurable increment widths through age 11. Two individuals read 369 sectioned otoliths and 116 whole otoliths; one individual read 155 scales twice. Precision between readers and aging methods was relatively high (average percent error, 1.5–4.5). Comparison of ages from scales and whole and sectioned otoliths from 154 fish showed no significant differences (P≤ 0.05).