Purpose: To evaluate the validity, reliability, and sensitivity of the novel Means-End Problem-Solving Assessment Tool (MEPSAT). Methods: Children with typical development and those with motor delay were assessed throughout the first 2 years of life using the MEPSAT. MEPSAT scores were validated against the cognitive and motor subscales of the Bayley Scales of Development. Intra- and interrater reliability, developmental trends, and differences among groups were evaluated. Results: Changes in MEPSAT scores positively related to changes in Bayley scores across time for both groups of children. Strong intra- and interrater reliability was observed for MEPSAT scoring across all children. The MEPSAT was sensitive to identify change across time and differences in problem-solving among children with varying levels of motor delay. Conclusions: The MEPSAT is supported by validity and reliability evidence and is a simple tool for screening early problem-solving delays and evaluating change across time in children with a range of developmental abilities. What this adds to the evidence: The novel MEPSAT is supported by validity and reliability evidence. It is sensitive to detect problem-solving differences among young children with varying motor ability and to capture changes in problem-solving across time. It requires minimal equipment and time to administer and score and, thus, is a promising tool for clinicians to screen for early problem-solving delays or to track intervention progress in young children with or at risk for problem-solving delays.