Proficiency in problem solving is an important outcome in early childhood necessary for cognitive and emotional development. The development of an individual growth and development indicator of problem solving for children 1 to 4 years of age is described. Based on the general outcome measurement approach (Deno, 1997), the measure is intended for use by early childhood educators and interventionists in the education and identification of children having difficulty acquiring problem-solving skills and for monitoring children's progress during the course of interventions and early childhood. Results from a sample of 30 children demonstrated the superiority of an indicator comprised of Functions + Solutions toy play behaviors from among indicators based on four potential key skills and two composites. The Functions + Solutions indicator was superior in sensitivity to growth over time, psychometric properties, and practicality for use by early interventionists. Implications for future research and practice are discussed. (Contains 4 figures and 2 tables.)