Longitudinal evidence has demonstrated that engagement in physical activity (PA) and the development of motor competence (MC) have numerous tangible health and developmental benefits [1]. Preschool children are thus in an important stage for physical, mental and social development [2]. Likewise, early childhood (the period encompassing the preschool ages, 3–5 years old) is considered to be an important phase for developing fundamental movement skills (FMS)[3], apparently by attaining adequate levels of PA [1]. The research evidence suggests that most preschool children do not accumulate adequate levels of PA [4], which directly impacts MC, with low levels at the primary school age [5–7]. The negative effects of poor PA associated with low MC seem to be affected by individual characteristics and the physical and social environment [5, 8, 9]. This is particularly important for low SES children living in low-income areas, girls, individuals with no siblings at home and/or the relative age effect (RAE), since these correlates seem to influence children’s PA and MC [5, 10–12].

This Special Issue is devoted to systematic evaluations of PA and MC, all of which have an impact on preschool children’s knowledge of themselves and their movement possibilities. We here summarize the most important findings of the different contributions published in this Special Issue.