The goal of this review of the clinical and research literature is to identify, describe, and critique published methods for assessment of attention and related functions in preschool children (ages 6 and younger). The need for valid assessment of preschool children has grown dramatically in the past two decades following the implementation of special education services for infants, toddlers, and preschoolers under Public Law 99-457. At the same time, the number of preschool children presenting to clinicians for assessment of attention problems has grown at a steady rate. In contrast to assessment methods for school-age children, the availability of reliable and valid measures of attention for preschool children is much more limited. The majority of instruments developed to measure attention in preschoolers are described in the experimental literature, with fewer available commercially. Attention tests that can be appropriately used with children aged 3 and younger are scarce. Most preschool tests of attention report validity data involving sensitivity in contrasting clinical groups to controls, while the literature describing the utility of these measures in differentiating between clinical groups is much more limited. The review provides information on performance based tests (e.g., continuous performance, cancellation, auditory/visual span), as well as parent and teacher rating scales. The review concludes that valid assessment of attention and related skills can be effectively achieved in preschool children, with appropriate cautions. (Contains 1 table.)