The study found that perpetrator-victims of Internet harassment and unwanted sexual solicitation have emerged as a particularly important group for adolescent health professionals to be aware of, identify, treat, or refer into services. The majority of youth were not frequently involved in Internet harassment or unwanted sexual solicitation either as victims or as perpetrators. Among those who were involved, a multitude of psychosocial problems were apparent. This was true for youth involved as both perpetrators as well as victims of both internet harassment and sexual solicitation. The sample of 1,588 youths, aged 10 to 15 years old, who had used the Internet a least once in the last 6 months was administered the national cross-sectional online survey, The Growing Up with Media Survey. Cluster analysis was conducted with four scales: Internet harassment perpetration, Internet harassment victimization, unwanted sexual solicitation perpetration, and unwanted sexual solicitation victimization. Involvement in Internet harassment and unwanted sexual solicitation was associated with concurrent reports of psychosocial problems including substance use; involvement in offline victimization and perpetration of relational, physical, and sexual aggression; delinquent peers; a propensity to respond to stimuli with anger; poor emotional bond with caregivers; and poor caregiver monitoring as compared with youth with little to no involvement. This phenomenon was especially true for perpetrator-victims of Internet harassment and unwanted sexual solicitation. Findings were replicated using a frequency-based definition of involvement, suggesting that cluster analysis is useful in identifying subgroups of youth and can be used to guide frequency-based definitions, which are easier to implement across study samples. Tables, references