Early life history of largemouth bass (Micropterus salmoides) at Lake George and adjoining sloughs, Anoka County, Minnesota, is described. Bass spawning first occurred 2-5 days after mean daily water temperature exceeded 60° F. Two hundred and sixty-six nests were found on needlerush, waterlily roots, humps of fibrous material, aquatic vegetation, and sand in 10 to 62 inches of water. Egg survival at time of hatching varied from 0 to 94 percent. Percentage of successful nests from a single spawning period varied from 0 to 100. Number of fingerlings per brood 2 weeks after rising from the nest varied from 500 to 12,715 fish with mean brood size of 5,600 in 1956 and 1957 and 3,600 in 1958. Analyses of bag-seine catches showed 1.0, 5.5, 10.0, and 1.3 fingerlings per 1,000 square feet in 1955, 1956, 1957, and 1958, respectively. Number of yearlings in the four year classes at the beginning of the second summer of life were 0.05, 0.42, 0.93, and <0.05 per 1,000 square feet. Year classes were weak in 1955 and 1958 and strong in 1956 and 1957. Year-class strength was set after egg deposition and before fingerlings were 2 weeks old. Water temperature was directly related to egg survival and nest success. Wind was the most important single factor in year-class formation in Lake George. Egg survival was highest on needlerush and lowest on sand. Two-thirds of all successful nests were in water deeper than the median depth. Illumination, dissolved oxygen, total alkalinity, hydrogen-ion concentration, cannibalism, predation, food habits, growth rate, and condition were not factors in determining year-class strength.