Eggs from Lake Michigan alewives (Alosa pseudoharengus) were incubated at 79 different temperatures from 42.1 to 87.0 F. Hatching occurred at 44.4-84.9 F and was optimum (38% hatched) at about 64 F. Incubation time varied from 15 days at 45 F to 3.7 days at 70 F and 2.1 days at 84 F. Time from start to finish of hatching ranged from 13 days at about 46 F to 2-3 days at 68-70 F and 1-2 days at 80-84 F. Survival of unfed larvae held at incubation temperatures increased from 3.8 days at 51 F to 7.6 days at 58-59 F and then decreased to 2.4 days at 80-82 F.