Supported by a large body of work demonstrating the impact of infant attachment representations on subsequent development, numerous therapeutic programs have been developed to promote secure attachment, with increasing focus on parental mentalizing. Nonetheless, empirical evidence supporting their effectiveness has yet to be fully established. The current pilot study (N = 24) was designed to evaluate whether and to what extent parents' shifts in parental mentalizing following a brief attachment-based group intervention, namely circle of security parenting (COSP; Cooper, Hoffman & Powell, 2009) can be captured using the parental embodied mentalizing instrument (PEM; Shai & Belsky, 2017). Compared to a waiting list–control group, this small-scale study examined whether community-based low-risk mothers of infants aged 5–48 months show an increase in their observed PEM capacities following the intervention. Secondary self-reported outcome variables parental stress, feeling of competence, and self-compassion. Findings show that PEM ratings improved significantly over time in the COSP group, but not in the control group. Intervention group mother–infant dyads also presented significantly longer embodied interactions communication post intervention compared to the control group. No effects of the COSP on parental stress, competence, or self-compassion were found. Despite the small sample size, these results tentatively suggest that COSP can improve embodied mentalizing abilities.