The MacArthur-Bates Inventories are a valid and reliable method for assessing communicative and linguistic skills in infants (8-15 months) and young children (16-30 months), and have been adapted to many languages. This paper presents their adaptation to Spanish. Structure, innovations included in the Spanish version, and the standardisation process are described, and some results obtained from the analysis of a sample of 1150 children are presented. The advantages and limitations of the use of parental report inventories are highlighted. For children before three years of age, there are very few assessment tools of language and communicative development with sufficient guarantees produced and edited in Spain. The Spanish version of the MacArthur-Bates Inventories represents an important contribution for early identification of language delays or disorders, and for follow-up of these cases.