A review was made of the recent research studies and descriptive articles which pertained to public library programs for young children. This review indicated, first, that very little significant empirical research or careful statistical studies exist which accurately measure and analyze either the validity of providing such services, their desired objectives, or their effects upon participants. Documentation of this situation is presented. Secondly, the review of the literature revealed that despite this scarcity of research, a great variety of public library programs for the youngest clientele are presently being offered. This article examines the few research efforts which have been undertaken which focus upon the evaluation of library programs for preschool children. Pertinent research from the related disciplines of reading and education are also included, with implications for the field of librarianship. In particular, the findings from the analytical research of this author which concerned the recommendations of early childhood education authorities regarding public library programs for children from infancy to six years of age, are presented. Lastly, this article contains guidelines and a philosophy statement for public libraries in serving preschool patrons and their caregivers which were developed based upon the conclusions of the research.