Early emerging executive functioning is associated with important emotional, social, and academic outcomes, including academic competence in elementary school. Employing a family study design, the current study investigated preschoolers' executive functioning and receptive vocabulary knowledge, maternal depression and anxiety measured when the children were in preschool, and elementary school academic competence longitudinally. The primary aim of the research was to examine relations between preschooler executive functioning and receptive vocabulary, maternal depression and anxiety, and parent-rated elementary school academic competence. Families with two children between 2.5 and 5.5 years of age (n = 198; mean age = 3.88, SD = 1.04) participated in online surveys, a laboratory visit, and another online survey after the children entered elementary school. Preschool inhibitory control and receptive vocabulary were significantly associated with academic competence in elementary school (but working memory was not), child age was related to preschool executive functioning and receptive vocabulary, and maternal depression was associated with preschool receptive vocabulary. Our longitudinal findings indicate that enhancing early inhibitory control and receptive vocabulary could support transitions to elementary school.