The relation of social and linguistic input measures to early vocabulary development was examined in 30 low-income African American mother-infant pairs. Observations were conducted when the child was 0 years, 1 month (0;1), 0;4, 0;8, 1;0, 1;6, and 2;0. Maternal input was coded for word types and tokens, contingent responsiveness, and directiveness. Children's outcome measures included productive vocabulary at 1;6 and 2;0. Patterns of social and linguistic input were highly consistent over time. Significant positive relations were found between linguistic input measures and child vocabulary development. Findings for social input measures included positive relations between directive input and child word types, which differs from previous research with European American middle-class samples.