Lower extremity weakness has been documented in children with cerebral palsy (CP). However, the temporal characteristics of moment generation have not been characterized, and they may be important to function. This study tested ankle, knee, and hip flexion and extension moment generation capabilities in children with CP and in able-bodied children. Maximum voluntary isometric contractions (MVIC), the maximum rates of moment development and relaxation, and the time to produce and reduce the moments were quantified. Relationships between the temporal measures, Gross Motor Function Measure-66 (GMFM-66), and MVICs were also examined. Children with CP had significantly reduced MVICs, maximum development, and relaxation rates, and increased times to produce and reduce moments. The maximum rates of moment development and relaxation at some joints were correlated with the GMFM-66 and MVICs. These results suggest that both the magnitude and temporal characteristics of moment generation need to be targeted during therapeutic interventions for children with CP.