The heterogeneity in the developmental trajectories of math motivational beliefs (i.e., expectancies for success and subjective task value beliefs) was examined among Asian and Latinx male and female students from Southern California across Grades 8 through 10 (n = 2,710; 50% female; 85% Latinx; 15% Asian; M[subscript age] = 13.77). By conducting…

Youth with greater levels of narcissism face a wide array of difficulties in interactions with others. However, there exists a curious lack of research on their close relationships, such as friendships. In this study, we examined associations between narcissism and friendship features over time. Participants were 261 eighth and ninth graders (112…

Peer victimization is a common concern in adolescence that includes both relational (e.g., exclusion, rumor spreading) and overt (e.g., hitting, threatening) forms (Crick & Bigbee, 1998). Relational and overt peer victimization have shown to be differentially associated with depressive symptoms, with relational peer victimization showing a…

Gender stereotypes about science, technology, engineering, and math (STEM) are salient for children and adolescents and contribute to achievement-related disparities and inequalities in STEM participation. However, few studies have used a longitudinal design to examine changes in gender stereotypes across a range of STEM fields. In a large,…

This study examined associations between perceived popularity trajectories and changes in proactive and reactive aggression in middle adolescence. The sample included 1,374 adolescents from 5 cohorts who were followed from Grade 7 to Grade 9 (49% males, M[subscript age] = 12.67 years, SD = 0.67). Popularity trajectories were identified based on…

Little is known about the naturalistic development of mindfulness in adolescence and how it relates to changes in emotional well-being. The current longitudinal study examined the development of one dimension of mindfulness, nonreactivity to difficult inner experience (or in more colloquial terms, being able to notice, but "take a step…

This study examines developmental change across adolescence in the similarity of friends versus nonfriends. This differential in similarity is a key aspect of the organization of the peer context of development: The stronger the correlation between friends for an attribute, the more the attribute delineates clustering and divisions of friendships.…

This research examined how children's inclusion of social personal attributes (e.g., talkative and argumentative) in their views of themselves changes over early adolescence in the United States and China. In 2 studies (N = 825 in Study 1 and 394 in Study 2) using open-ended methods (e.g., completion of "I ... " stems), American and…

Is compulsive Internet use (CIU) an antecedent to poor mental health, a consequence, or both? Study 1 used a longitudinal design to track the development of CIU and mental health in Grade 8 (N = 1,030 males, 1,038 females, M[subscript age] = 13.7), 9, 10, and 11. Study 2 extended Study 1 by examining the kinds of Internet behaviors most strongly…

This study examined the associations between children's co-occurring relational and physical aggression trajectories and their peer relations (i.e., peer rejection, peer acceptance, and reciprocated friendships) from late childhood (Grade 4; M[subscript age] = 10.0) to early adolescence (Grade 8; M[subscript age] = 13.9). Using a sample of 477…

Recent advances in positive youth development theory and research explicate complex associations between adaptive functioning and risk behavior, acknowledging that high levels of both co-occur in the lives of some adolescents. However, evidence on nuanced overlapping developmental trajectories of adaptive functioning and risk has been limited to 1…

While recent evidence has indicated that experienced racial discrimination is associated with increased depressive symptoms for African American adolescents, most studies rely on cross-sectional and short-term longitudinal research designs. As a result, the direction and persistence of this association across time remains unclear. This article…

The association of enumeration and number comparison capacities with arithmetical competence was examined in a large sample of children from 2nd to 9th grades. It was found that efficiency on numerical capacities predicted separately more than 25% of the variance in the individual differences on a timed arithmetical test, and this occurred for…

The self-equilibrium hypothesis underlines the importance of having a strong core self, which is defined as a high and developmentally stable self-concept. This study tested this hypothesis in relation to body image (BI) trajectories in a sample of 1,006 adolescents (M[subscript age] = 12.6, including 541 males and 465 females) across a 4-year…

Using a sample of 767 children (403 girls, 364 boys), this study aimed to (a) identify groups with distinct trajectories of peer victimization over a 6-year period from primary school through the transition to secondary school, and (b) examine the associated personal (i.e., aggression or internalizing problems) and familial (family status,…