The purpose of this study was to compare the use of molding helmet therapy in the treatment of positional brachycephaly and posterior positional plagiocephaly. Four hundred twenty-eight children with positional brachycephaly or plagiocephaly were included in this study. In this group of patients, 132 (32%) were treated with positioning alone. Of the 292 (68%) patients who were treated with molding therapy, 64 (21.9%) were treated for positional brachycephaly and 248 (78.1%) were treated for posterior positional plagiocephaly. All children were evaluated by a craniofacial surgeon and a pediatric neurosurgeon. Anthropomorphic measurements were used to assess the efficacy of treatment. Measurements were made before initiation of therapy and at 2-month intervals until the completion of therapy. Results showed that statistically significant improvements (P < 0.01) were seen in all patients treated with molding helmet therapy. Overall, the children with posterior plagiocephaly normalized their head shapes; however, the head shapes of the children with positional brachycephaly did not normalize despite statistically significant improvements in their Cephalic Index. It is concluded that molding helmet therapy is an effective treatment of position-induced head shape abnormalities. Helmet therapy is more effective in children with posterior positional plagiocephaly than in children with positional brachycephaly.