The aim of this study was to examine whether it was possible to develop a reliable and valid assessment of reflective parenting implicit in interaction with school-aged children using an adaptation of the Squiggle paradigm developed by Winnicott ( 1968 ) and a manualized coding system (Normandin, Leroux, Ensink, Terradas, & Fonagy, 2015 ). A total of 158 mother-child dyads participated when children were age 5 to 12. Of this group, 89 children had experienced sexual abuse. Interrater reliability using the manualized coding system was excellent. The factor analysis identified a reflective parenting stance factor, in addition to an affectionate support factor and a negative parenting factor. Furthermore, there was a medium strength relationship between the mother's reflective parenting stance evident in her interactions with her child and parental reflective functioning assessed using the Parent Development Interview (Slade, Aber, Bresgi, Berger, & Kaplan, 2004 ), suggesting the parental reflective stance is a good indicator of parental reflective functioning in interaction. With regard to parent reports of child internalizing and externalizing behaviors, the reflective parenting stance was the only predictor of internalizing difficulties and a significant predictor of externalizing difficulties in addition to sexual abuse.