Several studies have demonstrated a relation between executive functioning (EF) and theory of mind (ToM) in preschoolers, yet the developmental course of this relation remains unknown. Longitudinal stability and EF-ToM relations were examined in 81 children at 24 and 39 months. At Time 1, EF was unrelated to behavioral measures of ToM but was significantly related to parent report of children's internal-state language, independent of vocabulary size. At Time 2, behavioral batteries of EF and ToM were significantly related (r = .50, p < .01). Furthermore, EF (Time 1) significantly predicted. ToM (Time 2), independent of several controls. A reciprocal relation (internal-state language → EF at Time 2) was nonsignificant with the controls included. Individual differences in EF were relatively stable.