Purpose-We examine longitudinal relationships between virginity pledging in adolescence and both sexual initiation and condom use. Prior studies have had mixed results and may not adequately control for pre-pledge differences between pledgers and non-pledgers.Methods-Data came from a national sample of 12-17 year olds surveyed in 2001 and reinterviewed 1 and 3 years later. Logistic regression models estimated the association between making a pledge and each outcome. Selection bias was reduced through propensity-score weighting and a rich set of demographic and psychosocial covariates.Results-Pledgers and non-pledgers differed substantially in pre-existing characteristics. However, after propensity-weighting and statistical controls, pledging was still associated with delayed intercourse. We estimate that in the absence of pledging 42.4% of virgins with characteristics indicating an inclination to pledge initiate intercourse within 3 years; in the presence of the pledge, 33.6%of such youth initiate intercourse. Among those who had sex during this period, pledging was unassociated with condom use. Among those who did not have sex during this period, pledging was unassociated with engagement in noncoital sexual behavior.Conclusions-Making a virginity pledge appears to be an effective means of delaying sexual intercourse initiation among those inclined to pledge without influencing other sexual behavior; pledging does not appear to affect sexual safety among pledgers who fail to remain abstinent.Nearly 800,000 teenagers become pregnant in the U.S. each year [1] and half of the approximately 19 million new STD infections diagnosed annually are among youth 15 to 24 years old [ 2]. Unplanned pregnancies and STDs are more common among those who begin sexual activity earlier [3]. Delaying sexual activity might therefore have important public health consequences.One approach to delaying sexual activity is the virginity pledge -a public declaration to abstain from sex until marriage. The first virginity pledge program was True Love Waits, founded by the Southern Baptist Church in 1993. The movement has since grown to include hundreds of churches, schools, and colleges across the country. Among adolescents in the United States, it is estimated that 23% of females and 16% of males have made a virginity pledge [4]. From a theoretical perspective, pledging may work by enhancing social norms to abstain from sex [ 5]; pledgers may believe, more so than others, that they will be held responsible to their peers or important adults to follow through on their public commitment.Correspondence regarding this manuscript can be sent to Steven C. Martino, RAND, 4570 Fifth Avenue, Suite 600, Pittsburgh, PA 15213-2665. Tel: 412-683-2300, ext. 4629. Fax: 412-683-2800 Through processes of cognitive dissonance or self-perception [6][7], pledging may also lead youth to internalize the commitment or values expressed in the pledge.Although these programs may delay sex, those who make a virginity pledge but fail to keep it may actually i...