The Clinical Observations of Motor and Postural Skills (COMPS) is a screening tool for children with motor incoordination. A study of reliability (test-retest, interrater, and internal consistency) and construct validity with 132 children, both with and without developmental coordination disorder, is reported here. Test-retest reliability over 2 weeks was high: .92 for a group of 48 children. Interrater reliability for occupational therapists experienced in pediatrics was also excellent: .87 for a group of 72 children. Internal consistency of the COMPS was high, particularly when one of the seven items (Schilder’s arm extension) was deleted. The test discriminates well between children with and without motor problems and has many properties of a good screening test.