We reported previously that a moderate level of fetal alcohol treatment reduces the birth, maturation, and migration of serotonin (5-HT) neurons at embryonic days 11 to 15 (E11-E15). Because 5-HT is known as a differentiation signal for forebrain development, we investigated whether alcohol affects 5-HT innervation to the developing brain and how the target brain areas grow as they receive 5-HT innervation between E15 and E18.