Given the potential long-term outcomes of poorly developed mathematical skills, there is a need to understand the emergence and development of these skills in the context of improving educational experiences and ensuring better outcomes for preschoolers. The purpose of this article is to describe preliminary reliability and validity evidence supporting the Preschool Numeracy Indicators (PNIs), which are tasks for the assessment of number skills during the preschool years. Results from a sample of 3- to 6-year-old children (N = 163) attending preschool and Head Start programs revealed (a) evidence of test-retest reliability, (b) evidence that the four PNIs measure the same construct, (c) evidence of age-related differences in PNIs scores, and (d) evidence that the PNIs demonstrate external relations with scores from three test batteries measuring mathematics and number skills and other preacademic skills. Implications focus on the use of the PNIs for screening purposes, and future research is described. (Contains 6 tables and 11 footnotes.)