Running head: Trajectories of Anxiety in Adolescence General Growth Mixture Analysis of Adolescents’ Developmental Trajectories of Anxiety: The Impact of Untested Invariance Assumptions on Substantive Interpretations Alexandre J.S. Morin *, Ph.D. Group for Interdisciplinary Research in Psychology Applied to Social Systems (GIRPASS), Department of Psychology, University of Sherbrooke, Canada Christophe Maïano *, Ph.D. UMR 6233, Institute of Movement Sciences, Etienne-Jules Marey, CNRS-University of Aix-Marseille II, Marseille, France. Benjamin Nagengast, Ph.D. Self-concept Enhancement and Learning Facilitation (SELF) Research Group, University of Oxford, UK Herbert W. Marsh, Ph.D. Self-concept Enhancement and Learning Facilitation (SELF) Research Group, University of Oxford, UK Julien Morizot, Ph.D., University of Montreal Public Health Research Institute, School of Psychoeducation, University of Montreal, Canada Michel Janosz, Ph.D. School Environment Research Group, School of Psychoeducation, University of Montreal, Canada * The first two authors (A.J.S.M. and C.M.) contributed equally to this article and their order was determined at random: both should be considered first authors. This is a prepublication version of a manuscript to be published by Structural Equation Modeling. This paper should be referred as: Morin, A.J.S., Maïano, C., Nagengast, B., Marsh, H.W., Morizot, J., & Janosz, M. (accepted). General Growth Mixture Analysis of Adolescents’ Developmental Trajectories of Anxiety: The Impact of Untested Invariance Assumptions on Substantive Interpretations. Structural Equation Modeling. Accepted on December 2nd 2010. Acknowledgements This study was made possible by a grant from the Social Sciences and Humanities Research Council of Canada (SSHRC) awarded to the sixth author. The authors wish to thank every student, staff member and research assistant involved in the MADDP. Corresponding author: Alexandre J.S. Morin University of Sherbrooke Department of Psychology 2500 boulevard de l’Université Sherbrooke, QC J1K 2R1 Canada E-mail: alexandre.morin@usherbrooke.ca