Parent report can provide valuable information on early child language development for clinical and research purposes. Previous research has documented the validity of parent report as an overall assessment of child language and as a measure of expressive vocabulary. In this project, a newly revised questionnaire for the assessment of vocabulary and syntactic development, the MacArthur Communicative Development Inventory: Toddlers, is evaluated. Twenty-four children at 24 months were seen for a laboratory assessment including the Expressive One-Word Picture Vocabulary Test, the Memory for Sentences subtest of the Stanford-Binet Intelligence Scale: Fourth Edition, and selected items of the Sequenced Inventory of Communicative Development. In addition, a language sample was recorded, from which mean length of utterance and other measures were derived. Concurrent validity correlations demonstrate high validity for parent report in both domains (r = .73-.79), and some ability to differentially assess the two.