Variability in a way and velocity of language development among children have been claimed in numerous studies. Current goal in the field of language development studies is to define an impact of variety among external and internal factors on developmental processes. Currently, of special interest are demographic factors (gender, birth order and maternal education) that are considered to have a strong role in determining the guideposts of language development. Studies of influence of demographic factors on language development have primarily been preformed with parental reports instruments, such as MacArthur Bates Communicative Development Inventories (MB-CDI). Hence, the purpose of this research was to examine the correlation between demographic factors (gender, birth order and maternal education) and language development (productive vocabulary and ability to combine words). The participants (age 16-30 months) were children (N=140) who were divided into three age groups (16-19, 20-24, 25-30 months). Data originate from Croatian short form of Komunikacijske razvojne ljestvice (Communication developmental scales; currently in adaptation)- Riječi i rečenice (Words and Sentences) that were completed by the parents of the children. Correlations between two language variables (productive vocabulary and abilty to combine words) indicate a moderate connection between productive vocabulary and child's ability to combine words in two groups- 16 - 19 and 25 - 30 months of age. High correlation between those two language variables has been found in the age group from 20 - 24 months. Block of demographic factors has been found as statistically significant for predicting language development only in a period between 20-24 months. Also, gender was found as only independent significant factor that has a strong predictive role in language development at that age.