The Alabama Parenting Questionnaire nine-item short form (APQ-9) is an often used assessment of parenting in research and applied settings. It uses parent and youth ratings for three scales: Positive Parenting, Inconsistent Discipline, and Poor Supervision. The purpose of this study is to examine the longitudinal invariance of the APQ-9 for both parents and youth, and the multigroup invariance between parents and youth during the transition from middle school to high school. Parent and youth longitudinal configural, metric, and scalar invariance for the APQ-9 were supported when tested separately. However, the multigroup invariance tests indicated that scalar invariance was not achieved between parent and youth ratings. Essentially, parent and youth mean scores for Positive Parenting, Inconsistent Discipline, and Poor Supervision can be independently compared across the transition from middle school to high school. However, comparing parent and youth scores across the APQ-9 scales may not be meaningful.