The aim of this study was to develop a model of identity formation comprising three structural dimensions: commitment, in‐depth exploration and reconsideration of commitment. A new tool, the Utrecht‐Management of Identity Commitments Scale, was designed to assess these processes. Early and middle adolescents (N=1952) participated in this study. Confirmatory factor analyses revealed that the three‐factor model provided a better fit than alternative one‐ and two‐factor models. The model applied not only to the whole adolescent sample, but also to male and female subsamples and to early and middle adolescent age groups. Additionally, we established interethnic equivalence of the model, in that it also fit well for ethnic minority adolescents. In accordance with hypotheses, regression analyses showed that commitment, in‐depth exploration and reconsideration of commitment were significantly related to measures of self and personality, psychosocial problems and parent–adolescent relations. Implications and suggestions for future research are discussed.

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Cannabis use is a heritable trait that has been associated with adverse mental health outcomes. In the largest genome-wide association study (GWAS) for lifetime cannabis use to date (N = 184,765), we identified eight genome-wide significant independent single nucleotide polymorphisms in six regions. All measured genetic variants combined explained 11% of the variance. Gene-based tests revealed 35 significant genes in 16 regions, and S-PrediXcan analyses showed that 21 genes had different expression levels for cannabis users versus nonusers. The strongest finding across the different analyses was CADM2, which has been associated with substance use and risk-taking. Significant genetic correlations were found with 14 of 25 tested substance use and mental health-related traits, including smoking, alcohol use, schizophrenia and risk-taking. Mendelian randomization analysis showed evidence for a causal positive influence of schizophrenia risk on cannabis use. Overall, our study provides new insights into the etiology of cannabis use and its relation with mental health.

Longitudinal research into personal and ethnic identity has expanded considerably in the first decade of the present century. The longitudinal studies have shown that personal identity develops progressively during adolescence, but also that many individuals do not change identity, especially ethnic identity. Researchers have found rank-order stability of personal identity to be larger in adulthood than in adolescence and stability of ethnic identity to be larger in middle and late than early adolescence. Personal identity appears to progress in adulthood, as well. Adolescents with a mature identity typically show high levels of adjustment and a positive personality profile, live in warm families, and perform well at school. There is little evidence for developmental order, however, and studies instead have mainly found covariation over time between identity and the other developmental processes. The present review demonstrates that the dimensional approach to the study of identity formation can be very successful. It allows for combined variable and person-centered analyses, and for empirically generated and replicable statuses. Theoretically, the review suggests that identity formation is a less dynamic process than commonly assumed, that the identity status continuum has the order diffusion (D) ! moratorium (M)