The development of the minimal self - distinguished in the facets sense of agency, body ownership, and interoception – has recently gained attention in developmental science. While research proposes the presence of minimal self facets in young children, interrelations among the three facets and cognitive mechanisms driving their development remain debated. Current theories suggest that minimal self facets are dynamic and plastic, affected by top-down processes and cognitive representations. To advance developmental theorizing, the present registered report had four aims. It a) examined how strongly the three minimal self facets are related, and b) investigated the impact of one central cognitive process – the internal working model (IWM) of attachment – on young children’s explicit self, and c), their minimal self. Furthermore, it d) explored whether the impact of the IWM is particularly strong in emotional contexts. A total of 120 fiveyear-old children from an urban German area participated. Established measures were used to assess all three minimal self facets, explicit selfconcept, and dimensional security of attachment IWM. We found no significant relations between the three minimal self facets and no prediction of minimal self facets by attachment security. Thus, the study provides no evidence for an influence of attachment IWM on minimal self facets in childhood. Exploratory analyses showed a relation between attachment categories and the malleability of sense of body ownership suggesting that a categorical approach to attachment is relevant for considerations of minimal self facets. We suggest that future research should integrate the sensorimotor grounding of attachment.