The objective of this study was to describe prevalent informal sources of information about sex and examine associations between informal sources of information about sex and sexual risk outcomes among sexually experienced adolescents. Work involved the secondary analysis of data from the Minnesota Student Survey, a statewide survey to monitor priority risk and protective health behaviors. The study sample included 22,828 sexually experienced adolescents aged 13-20 years. Multivariate logistic regression analyses examined associations between adolescents' informal sources of information about sex and three sexual risk outcomes. Peers and siblings were the most commonly reported source of information about sex. Ninth-graders who reported parents or parents plus peers/siblings as a source of information about sex had significantly lower odds of having multiple sex partners in the past year. Ninth-graders who reported any informal source of information about sex had significantly lower odds of unprotected intercourse at last sex. Ninth-graders and 12th-graders who reported any informal source of information about sex had significantly lower odds of lifetime pregnancy involvement. Findings suggest information about sex from people in adolescents' everyday lives has the potential to diminish the likelihood of involvement in sexual risk behaviors. To maximize effectiveness, formal sex education programs should engage informal sources of information about sex in adolescents' everyday lives. (Contains 2 tables and 1 figure.)