The purpose of the present study was to develop and psychometrically evaluate a new measure of parental perceptions grounded in the Eccles' parental socialization framework: the Parents' Perceptions of Physical Activity Importance and their Children's Ability Questionnaire (PPPAICAQ).Cross-sectional with self-reported questionnaires.The total sample comprised 1100 parents of children (6–11 years old) and was randomly divided in third (one calibration and two validation samples). Data were analyzed with reliability, confirmatory factor analyses (CFA), multi-group CFAs as well as with correlational analyses.Results of the initial confirmatory factor analyses (CFAs) of the 2-factor 12-item model on the calibration sample resulted in a poor fit to the data. Re-estimation of the PPPAICAQ resulted in the deletion of 4 initial items. The 2-factor 8-item model revealed a good fit to the data for the three samples. Results of two multiple-group CFAs showed that the final model was partially invariant across the father and mother as well as the boy and girl samples. The patterns of relationships between parents' motivation, parents' support and the PPPAICAQ subscales provided evidence for the criterion-related validity of the PPPAICAQ.This study provided support for the reliability and validity of the PPPAICAQ. The PPPAICAQ is an instrument that will be useful for theoretically-driven research on parental socialization influence on children’ PA.