Purpose: This research explored the impact of neighborhood density (ND), word frequency (WF), and word length (WL) on the vocabulary size of Danish-speaking children. Given the particular phonological properties of Danish, the impact was expected to differ from that reported in studies on English and French. Method: The monosyllabic words in the expressive lexicons of 894 Danish-speaking 2-year-old children were coded for ND, WF, and WL. Lexicons were extracted from parent checklists of the words spoken by their children. Results: Regression revealed that ND, WF, WL, and age together predicted 47% of the variance in vocabulary size, with ND, WF, WL, and age uniquely accounting for 39%, 3.2%, 2.2%, and 2.8% of that variance, respectively. Children with small vocabularies had learned words that were denser and more frequent in the ambient language, and those words were shorter than the words of children with larger vocabularies. Conclusion: The 2 main findings were unexpected. The impact of ND for Danish-speaking children was not expected given the phonological properties of the language. The WF results differed from those of English because of the distribution of word classes on the language-relevant parent checklists. The strong role for ND in emerging languages found in other languages was replicated for Danish.