Just 19% of children in Ireland get the recommended 60-minutes of moderate-vigorous physical activity per day, therefore culturally relevant initiatives aimed at increasing physical activity (PA) are urgently needed. Physical Literacy (PL) is purported to be a pathway towards Physical Activity (PA) and health, with Fundamental Movement Skills (FMS) being a core component of the accepted PL model. Another factor linked with FMS is Health-Related Fitness (HRF), and HRF has shown positive associations with health. Phase One of this study comprised of a nationwide assessment of a broad range of FMS, and all the HRF components across primary school-children (n=2098, 47% girls, age 5-12 years) in order to ascertain a true reflection of Irish children’s FMS and HRF status. Irish children demonstrated low levels of FMS mastery (25.2% - 56.7%), with boys significantly outperforming girls in object control skills (p<0.001, eta squared = 0.08 – 0.13). Improvements in ability were evident with age, with FMS proficiency increasing significantly up to ten years of age, after which a plateau in proficiency occurred. Age-related differences in the FMS-HRF relationship were also found, with a positive association between FMS and HRF that strengthened with age (β = -0.189 – 0.393). The next phase assessed the efficacy of a unique and novel exploratory trial aimed at increasing FMS in Irish primary school children (n = 417, 52% female, age = 7.6 ±0.66). Multilevel analyses revealed significant interaction effects across time for the intervention group (p<0.001, d = 1.5). Overall, findings highlight low levels of FMS proficiency in Irish children, and the need for a strong focus on FMS with young children, through a PL lens. These findings suggest that an intervention, such as outlined in this document, could help increase PA levels, PL in general, and in turn, increase the positive health benefits associated with PA.