The 1956 catch of Atlantic menhaden (Breyoortia tyrannus) amounted to 766,000 tons. Apparent abundance, as measured by catch per purse-seine set, was highest in the North Atlantic Area and lowest in Chesapeake Bay. Geographical distribution of fishing effort is shown. Samples for age, size, and sex determinations were obtained from the purse-seine and pound-net catches landed from Fernandina Beach, Florida, to Portland, Maine. Age composition showed that the 1955 years class (age-1 fish) accounted for more than half of the total catch. This year class dominated the summer catches in the South Atlantic and Chesapeake Bay Areas as well as the fall catches in North Carolina, while the 1954 year class (age-2 fish) dominated in the Middle Atlantic Area, and the 1951 year class (age-5 fish) dominated in the North Atlantic Area. Fish of the dominant year class in each of these areas were smaller in 1956 than in the previous year.