This paper reviews current literature concerning the development of children's comprehension of the processes of natural languages and it recommends a new study approach designed to evaluate the joint effects of lexical and syntactic devices on comprehension. It discusses three main kinds of investigations--studies of the comprehension of individual words and suprasegmentals, studies of information gain, and studies of the comprehension of syntactic processes--as well as testing techniques and the specific syntactic and morphological processes considered. Results of particular studies are given. The second part of the paper covers the necessity of treating language as a structure rather than as individual words when testing comprehension, and it recommends a conceptual-category approach which considers the relationship between formal linguistic processes and cognitive relations by showing how well language is comprehended in specific language-use situations. (VM)