Additional Study Information: This study is for patients with melanoma, non-small cell lung cancer (NSCLC), or squamous cell cancer of the head and neck (SCCHN) that has a protein called B7-H3 on the tumor cells or blood vessels in thetumor. The purpose of this study is to test the safety, tolerability, and most effective dose ofMGA271 in combination with ipilimumab (also called Yervoy) This study will also evaluate how much MGA271 and ipilimumab are in the blood at various times, whether the immune system becomes activated following treatment, as well as the effects MGA271 and ipilimumab have on the cancer. The information learned in this study may be helpful in the further development of MGA271 and ipilimumab for the treatment of cancer.