The purpose of this guide is to provide a short, ready source of information about the process and problems of the diagnostic assessment of preschool children. Formal test instruments frequently used in the assessment process are listed by category. Detailed discussions of the tests and useful information the classroom teacher can gain from the results are included. Test instruments listed were chosen for their apparent frequency of use in the field of early childhood education. Inclusion in the list does not signify approval by the authors or the sponsoring program. Efforts have been made to keep terminology and jargon to a minimum. Necessary professional terms are defined either in context or in the glossary. The first chapter describes the process and problems of assessment. Reliability, validity, measures of central tendency, and standard scores as well as test scores in relation to classroom performance are discussed in Chapter II. Chapter III discusses how tests are standardized, how the tests may be used, and what information test users should know about a test before it is employed in assessment. Chapters IV, V, VI, and VII provide information about intelligence, academic and pre-academic, speech and language, and visual perception and sensory motor tests, respectively. Chapter IX lists publishers and their addresses. (RH)