An instrument designed to assess young children's communicative skills at 18 months is described. The instrument consists of a 103-item parental report checklist based on the Swedish version of the Communicative Development Inventories (SECDI). We present descriptive data from a study at the Swedish Community Health Care Centres, including parental reports of 1021 18-month-old children. The response rate was 88%. Performance at the 10th percentile consisted of 8 communicative gestures, 45 comprehended words, and 7 spoken words. The overall results indicate that the instrument is reliable and has validity approximating that of the SECDI. Furthermore, parents of the children with the poorest vocabulary indicated approval of the assessment procedure in interviews especially directed to this group.