This study sought to prove six hypotheses about the correlation between adolescents’ online use and parental behaviour, adolescents’ self-efficacy and adolescents’ self-regulation. Social Cognitive Theory (SCT) underpinned a survey of 340 respondents (182 males and 158 females) in the 12-17 year age group from 2 high schools in metropolitan South Australia. Structural Equation Modeling was used to test the significance of the hypotheses. The survey results revealed that environmental factors such as parental monitoring and guidance had a significant impact on adolescents’ online use. They also indicated that adolescents’ self-regulatory behaviour concerning online use may be influenced by other factors such as self-knowledge and self-determination. Personal factors such as instinct and motivation were found to influence the outcomes of online misuse, and encourage adolescents to adopt moderate and safe use patterns. The results demonstrated that self-efficacy – namely confidence, motivation and personality – has a positive impact on self-regulatory behaviour. A theoretical framework adapted from SCT specifically for this study generated new knowledge about factors that support a preventative approach to risky online use among adolescents.