The more common and more glaring pitfalls in developmental diagnosis encountered during infancy and early childhood have been outlined. Much of the ability to avoid these traps depends on a comfortable understanding of the four spheres of early child development and a sound familiarity with the principles of developmental assessment, especially the separation of intellectual and motor entities. Motor milestones are excellent indicators of motor competence but correlate poorly with intellectual capacity. Language and problem-solving milestones in infancy provide the best insights into a child's intellectual potential, and their evolution is independent of motor competence. They may be obscured by motor disability and as a result may be more difficult to demonstrate, but that is a separate issue. In that instance there is nothing subtle about the fact that one is already dealing with a disabled infant. Psychosocial abilities (affective milestones) are critical in understanding the whole child and in making a meaningful statement about behavior, but they lend little additional information to the assessment of intellectual and motor competence. For physicians the "curb-side consult" is a highly efficient tool that has great practical application to developmental concerns and especially to the avoidance of the pitfalls described. Every practitioner should have a resource in developmental and behavioral pediatrics with whom he or she can communicate in an informal fashion. This is especially valuable in situations in which the urgency or even the need for referral (a time-consuming, expensive, and often anxiety-provoking process) is not clear.