The purposes of the present study were to (a) explore the relationship between parent and teacher reports of children's bilingual (Spanish-English) productive vocabulary and (b) examine similarities and differences among parent-teacher reports. Word categories were examined to determine the nature of similarities and differences. Method: Parents and teachers of eleven Spanish-English bilinguals (M[mean] age = 44.5 months) completed the MacArthur-Bates Communicative Development Inventory upper extension and an experimental version of a congruent Spanish form at 2 time points. Percent agreement, kappa coefficient, and Spearman's rho were employed to estimate overall interrater agreement and agreement on specific word categories. Results: Results indicated inconsistent levels of overall agreement across measures and forms. Higher levels of parent-teacher agreement were observed on Spanish forms at either time point using Spearman's rho coefficient and kappa, whereas percent agreement was higher on English forms. Limited overlap of high agreement between parents and teachers was found on word categories across indices. Unique contributions of reporters were observed. Conclusion: This work underscores the utility of multiple informants of bilingual children's productive vocabulary. Combined and unique contributions of parent and teacher reporters may inform the language development of preschool-age bilingual children as productive vocabulary skills develop and change. (author abstract)