The importance of physical activity (PA) for optimal growth and development is well recognised, yet most Australian children do not achieve the recommended three hours per day. Fundamental motor skills (FMS) are the building blocks for complex movement patterns used in a range of sport and recreations including playground games and organised sport. The aim of this thesis is to determine effective methods of improving FMS and PA levels in preschool aged children. The literature review (chapter 2) examines how PA and FMS are defined and measured, and the factors associated with PA levels and FMS proficiency in preschool aged children. The systematic review and meta-analysis (chapter 3) examines the optimal intervention characteristics for increasing FMS proficiency and PA levels in children. Teacher-led interventions conducted three or more times a week are most effective at increasing FMS and showed trends towards increasing overall PA, especially moderate-vigorous PA levels in pre-school aged children. These optimal intervention characteristics were then applied in The PhysicaL ActivitY & FUNdamental motor skills Program (PLAYFun) presented in chapters 4 and 5. PLAYFun led to significant improvement in FMS proficiency between the PLAYFun and control groups at the completion of the intervention, however improvement was not maintained at 12-weeks post intervention, indicating the ongoing need for FMS practice. PLAYFun was time and resource intensive, limiting its widespread dissemination. Therefore, chapter 6 describes The Fundamental Motor Skills Movie Education for Parents Program (FUN MOVES), which was designed to overcome the resource intensive barrier of PLAYFun. FUN MOVES was developed to educate parents, through weekly videos, to teach their children FMS with an emphasis on skill development and acquisition. However, no significant differences were found between groups for measures of FMS or PA. The findings of the studies contained within this thesis found that face to face FMS program delivery is effective at increasing FMS proficiency in preschool children but is resource intense. Digital delivery of a FMS program to parents, whilst addressing the limitations of face to face delivery, may not be associated with significant improvement in FMS proficiency and warrants further study.