Background: Evidence suggests that sports participation improves wellbeing of youth. However, collision sports like football have become controversial due to evidence suggesting that football participation prior to the age of 12 may lead to worse cognitive and neuropsychiatric outcomes later in life. As few studies have examined how the intensity of collision and contact sports participation before age 12 relate to cognitive and emotional outcomes, we propose an observational study using the Adolescent Brain Cognitive Development (ABCD) dataset to determine how intensity of contact sports, collision sports, and non-contact sports participation during childhood relate to cognitive and emotional outcomes in early adolescence. Methods: Our proposed study includes 9974 youths from the ABCD dataset. For each child, we calculated a collision sport participation volume, contact sport participation volume, and non-contact sport participation volume. Our two primary outcomes are measured when the youths are aged 8.9-11.1 years old: the NIH Toolbox Cognition total composite score and the Parent Child Behavior Checklist (CBCL) total emotional problems score. We will fit a linear mixed effects model with our primary outcomes as the dependent variable and with contact sports volume, collision sports volume, non-contact sports volume, and demographic covariates as fixed effects and with random intercepts for family and site ID. The study will also involve secondary analyses of current sports participation exposures, specific sport exposures, and incident of traumatic brain injury (TBI) as a possible mediator. Discussion: This observational study will contribute to understanding how the volume of contact, collision, and non-contact youth sports participation relate to cognitive and emotional outcomes during a crucial developmental time window. This study will contribute to public health knowledge which will help stakeholders weigh benefits and risks of participation in different types of youth sports.