The role of language as a tool to support the self-regulation has been widely studied, yet there is little evidence on the role of prelinguistic communication in the early development of self-regulation. To address this gap, we developed behavioural indicators of preverbal cognitive self-regulation, and described how can parents support it through guided play. We observed 16 children at 14, 16 and 18 months interacting with two complex toys, either independently or with a parent. A microanalytic coding captured a total of 721 gestures, of which 473 were classed as self-regulatory. Children used gestures to support self-regulation in planning monitoring, control, and evaluation. Analysis of parental mediation revealed a relationship between supporting autonomy, providing challenge, responsiveness, effective communication, children's competence with objects, and self-regulatory gestures. We produced reliable indicators of self-regulation through gestures and characterized effective parental mediation, thus making explicit key social mechanisms to foster self-regulation in preverbal development.