Psychometric Properties of the English–Spanish Vocabulary Inventory in Toddlers With and Without Early Language Delay

Purpose: Despite the increasing population of dual language learners (DLLs) in the United States, vocabulary measures for young DLLs have largely relied on instruments developed for monolinguals. The multistudy project reports on the psychometric properties of the English–Spanish Vocabulary Inventory (ESVI), which was designed to capture unique cross-language measures of lexical knowledge that are critical for assessing DLLs’ vocabulary, including translation equivalents (whether the child knows the words for the same concept in each language), total vocabulary (the number of words known across both languages), and conceptual vocabulary (the number of words known that represent unique concepts in either language). Method: Three studies included 87 Spanish–English DLLs (M_age = 26.58 months, SD = 2.86 months) with and without language delay from two geographic regions. Multiple measures (e.g., caregiver report, observation, behavioral tasks, and standardized assessments) determined content validity, construct validity, social validity, and criterion validity of the ESVI. Results: Monolingual instruments used in bilingual contexts significantly undercounted lexical knowledge as measured on the ESVI. Scores on the ESVI were related to performance on other measures of communication, indicating acceptable content, construct, and criterion validity. Social validity ratings were similarly positive. ESVI scores were also associated with suspected language delay. Conclusions: These studies provide initial evidence of the adequacy of the ESVI for use in research and clinical contexts with young children learning English and Spanish (with or without a language delay). Developing tools such as the ESVI promotes culturally and linguistically responsive practices that support accurate assessment of DLLs’ lexical development. Supplemental Material: https://doi.org/10.23641/asha.17704391.