Adolescent externalizing behaviors as a general and persistent form of maladaptiveness have received widespread attention. In the past, research in the field of developmental psychology has focused more on the impact of risk factors on adolescent externalizing behaviors. Although these studies had an important role in reducing these behaviors, focusing on positive factors not only can reduce adolescent externalizing behaviors, but can also replace externalizing behaviors by promoting the development of positive behaviors. In recent years, studies have begun to examine the impact of positive factors on adolescent externalizing behaviors, and have identified multiple positive factors in the prevention of these behaviors. Few studies, however, have explored the accumulative impact of positive factors on adolescent externalizing behaviors. Concerning this topic, the developmental assets model provided us with an ideal research tool. Based on this model, the present study used a longitudinal study design to examine the cumulative effects of multiple developmental assets on adolescent externalizing behaviors. In addition, this investigation also examined the relationship model between cumulative developmental assets and externalizing behaviors, as well as the possible moderating roles of gender in this model. A sample of 1, 219 adolescents were recruited from three middle schools in Shandong, China. Quantitative surveys were administered to participants in December, 2015 (T1) and December, 2016 (T2). Adolescents only participated in the first survey, completing a self-administered questionnaire involving demographic variables and developmental assets. The head teachers participated in both surveys and completed an assessment of the externalizing behaviors of the students in their class. A series of analyses were conducted using SPSS 22.0 software, including descriptive statistics and correlation analysis, logistic regression analysis, and hierarchical multiple regression analysis. The results of the study were as follows: (1) the developmental assets had a cumulative effect on the reduction of adolescents' current and subsequent externalizing behaviors. In the cumulative effects relationship model, there was a differentiation between current and subsequent externalizing behaviors, which was characterized by the nonlinear pattern of the quadratic function between cumulative developmental assets and current externalizing behaviors, and a linear pattern between cumulative developmental assets and subsequent externalizing behaviors. (2) The moderating effect of gender was only significant in the nonlinear relationship of the quadratic function between the cumulative developmental assets and current externalizing behaviors. In short, the present study is the first to demonstrate the cumulative effects of developmental assets on adolescent externalizing behaviors, as well as the relationship model of the cumulative effects and the moderating effect of gender underlying the relationship model. This study provides a basis for targeted asset construction and the prevention of adolescent externalizing behaviors.