Language development is a complex process that is influenced by different factors, such as birth order and the presence or absence of siblings. Younger children benefit from hearing parentese directed to older siblings and from their older siblings' language models. Though current research does not reveal clear conclusions, the number of older siblings was negatively correlated with the amount of child-directed speech which may adversely affect language development in younger siblings. However, other research found that children with older siblings demonstrated more diverse receptive vocabulary knowledge. We hypothesize that children with one or two older siblings will demonstrate different general language performance than children without older siblings and number of older siblings will correlate with receptive and expressive language performance. Thirty-two four-year-old children were divided into groups having no, one or two older siblings. Language performance will be compared among these groups as well as relationships among the Clinical Evaluation of Language Fundamentals, preschool version 2, receptive and expressive subtests. The findings of this study will be discussed and compared with current research.