This study aimed to investigate the relationship between sit-to-stand (STS) movement, knee extensor torque and social participation in children with cerebral palsy (CP). Seven spastic hemiplegic CP patients (8.0 plus or minus 2.2 years), classified by the Gross Motor Function Classification System as I and II, and 18 typical children (8.4 plus or minus 2.3 years) participated in this study. Trunk, hips, knees, and ankles angles and temporal variables of STS movement were obtained by means of kinematics evaluation. Isokinetic evaluation was performed at 60 degrees/s in the concentric passive mode to measure knee extensors torque. Social participation was assessed by the Assessment of Life Habits for Children (LIFE-H) scale. Results showed that children with spastic hemiplegic CP have lower knee extensor torque in the affected limb and restriction in social participation in dimensions related with fine motor control and language skills when compared to their typical peers. Except for ankle excursion in frontal plane, and ankle excursion and range in transverse plane, patients were similar to typical children regarding the strategies adopted to perform the STS movement, as well as in the participation dimensions related with gross motor function. Moreover, we found a significant non-linear correlation between knee extensors torque and some lower limb and trunk angles for children with CP. Therefore, during evaluation and rehabilitation processes, impairments in body functions and structures should be related with how much they affect a child's ability to perform functional activities, so rehabilitation protocols could be focused on individual needs. (Contains 3 tables.)