The mechanisms through which socioeconomic status (SES) influences three-year-old expressive and receptive language abilities were examined in a sample of 1016 families from the NICHD Study of Early Child Care and Youth Development. Hierarchical regression analyses indicated that maternal sensitivity and cognitive stimulation were significant partial mediators of the relation between SES and verbal comprehension, expressive language, and receptive verbal conceptual abilities. Path analyses revealed that a unified model including both parenting factors and distal SES factors demonstrated solid fit indices. Implications for research and intervention are discussed.