Changes in odor preferences with age were assessed in house mice inhabiting a series of eight 0.1-ha outdoor enclosures. The most recent capture in a live trap was assumed to provide the predominant odor in that trap for one week. Data were analyzed for two separate years for females and males and for three age classes within each sex. Initial analyses confirmed the use of the odor baiting technique; significantly more mice than expected entered traps that had captured another mouse in the previous week relative to traps that had not caught a mouse for at least a week. For female mice two predictions were tested. (1) Young female mice avoid traps with odors from adult males. The findings support this prediction. (2) As they mature, female mice will shift their odor preference and enter significantly more traps odorized by adult males. The findings also support this prediction. Two predictions were tested for male mice. (3) Young male mice will avoid odors from adult males. The data do not support this prediction. (4) As they mature, males will shift their preference and enter more traps odorized by female mice. Some, but not all of the data support this hypothesis.