A major theme in early childhood education is that brain research has established the importance of early windows of opportunity that can be exploited to assure optimal brain development and life-long well-being. Explanations involving brain science have a seductive appeal, especially among the general public and policy-makers. Thus, neuroscientific evidence requires special scrutiny in the policy realm. Consideration of the neuroscience behind claims about windows of opportunity reveals a contrast between what is claimed in the policy as opposed to the scholarly literature. The advocacy literature tends to tell only half of the story about the effects of experience on synapse formation. The full story raises doubts as to how much specific guidance neuroscience can provide policy makers about what should go into those windows of opportunity.