The Macarthur-Bates Communicative Development Inventories (CDI) have been used widely to document early communicative development. The paper reports on a large community sample of 1,447 children recruited from low, middle and high socioeconomic (SES) areas across metropolitan Melbourne, Australia. Regression analyses were conducted to determine the extent to which communicative behaviours reported at 0;8 and 1;0 predicted vocabulary development at 1;0 and 2;0. In support of previous findings with smaller, often less representative samples, gesture and object use at 1;0 were better predictors of 2;0 vocabulary than were gesture and object use at 0;8. At 1;0, children from the lower SES groups were reported to understand more words than children from the higher SES groups, but there were no SES differences for words produced at 1;0 or 2;0. The findings add to our understanding of the variability in the development of early communicative behaviours.