Youth materialism excites adolescents’ unethical consumer beliefs (UCB-dishonesty). We develop a second-stage moderated mediation model, investigate the relationships between materialism and Generation Z teenagers’ consumer ethics (UCB-dishonesty), and treat two self-concept mechanisms (power and self-esteem) as dual mediators and culture as a moderator (China vs. France). We theorize that materialism enhances power (public self) and reduces self-esteem (private self). French adolescents’ sense of power increases UCB more than their Chinese counterparts. Chinese teenagers’ self-esteem reduces UCB more than their French counterparts. (...) We challenge the assumption that the interaction effects between consumers’ self-concepts and UCB are the same across cultures. We offer the following discoveries based on 1,005 (409 Chinese and 596 French) adolescents. First, the measurement model of consumer ethics with four subconstructs is superior to the model with one overall construct. Second, a sense of power and self-esteem mediate the relationships between youth materialism and consumer ethics, creating two positive and negative paths for power and self-esteem, respectively. Third, French adolescents display a higher magnitude and positive intensity between adolescents’ power (public self) and UCB-dishonesty than their Chinese counterparts across all four subconstructs. Chinese teenagers illustrate a lower magnitude but a higher negative intensity between self-esteem and UCB than their French counterparts across three subconstructs, with one exception: Adolescents’ self-esteem has no impact on “no harm, no foul” across cultures. Neither buyers nor sellers experience substantial financial gains or losses. Finally, cultures moderate the second-stage mediation effects. Scholars must enhance adolescents’ self-esteem and curb their power to promote honesty. We offer implications for materialism, consumer ethics, self-concepts, and culture for consumers and retailers. (shrink)