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We described quantitatively 19 summer plumage characteristics and bill and foot pigmentation of 247 known-age Laughing Gulls (Larus atricilla) collected in New York during 1992-1994. There were no differences in characteristics measured for male and female Laughing Gulls. Ninety percent of 2-yr-old Laughing Gulls and 96% of ≥ 3-yr-old birds had full hoods. Fifty-seven percent of 2-yr-old Laughing Gulls possessed at least partial tail bands in contrast to 4% of 3-yr-old and 0% of ≥ 4-yr-old gulls. Thus 2-and ≥ 3-yr-old Laughing Gulls cannot be separated reliably by the presence or absence of a tail band. Pink pigmentation on the breast or abdomen occurred in 12% of individuals and was unrelated to age. Using the presence or absence of a distinct black-and-gray interface on the distal portion of the fifth primary, we correctly classified 96% of 245 2- and ≥ 3-yr-old Laughing Gulls. Using this characteristic in combination with the length of distinct black pigmentation present on the proximal vane of the sixth primary, we correctly aged 98% o f 244 gulls. This technique and previously published plumage characteristics provide rapid and accurate classification of Laughing Gulls in summer plumage as < 1, 1, 2, or ≥ 3 yr of age.