We describe the development of a set of five equivalent checklists to assess word production of children in their second year. The words on each list do not overlap, but represent comparable levels of difficulty. Thus, individual lists may be used to estimate the child's production vocabulary, and the set of lists may be used serially in a longitudinal design.
A validation study on 25 infants suggests that the five lists produce comparable mean production scores, reflect differences in age, and preserve individual differences in total production and production of linguistic categories such as nouns, verbs, open class items, and closed class items. This finding provides further support for the reliability of parental report instruments in this developmental domain.