situation. The import'ance of understanding the extent and limitations of children's mastery of the logical connectives is evident for any cognitive theory of development, The recent rrork in psycholinguistics, emphasizing the c,olnplex nature of the granmar and senlantics of the language of children, has provided further impetus for seeking such understanding. It seems clear that the decelopment of a bet'ter theory about children's beha,vior and the changes in that behavior with age requires much more detailed infomlaiion about, their linguistic lmbits and competence than me now have. The present st'udy, which consists of two closely related experiments, is meant to contribute to the accumulation of such systematic information. The data of the experiment,s have been ana,lyzed in terms of several specific regression models to provide a deeper insight into what aspects of comprehension of sentential connect'ives are most difficult. The formal relations between various English idioms expressing conjunction, disjunction, and negation, and t'he set-theoretical operations of intersection, union, and complementation are not deeply explored in this paper, but our assumptions about these connections are obvious and uncontroversial. Deeper investigation of these linguistic and senuntical nlat'tere seems desirable as part of any further extensive study of children's conlprehension of logical connectives.