The objective of this Bureau of Mines investigation was to determine the effects of adding manganese compounds and ores to iron ore pellets. Manganese dioxide, carbonate, sulfate, and chloride, plus six manganiferous ores from the Minnesota Cuyuna Range were tested as additives to increase the manganese content of iron ore pellets. One to 5 percent manganese, as a compound or ore, was added to five magnetite concentrates and one hematite concentrate. These concentrates were balled, indurated (1,300 deg c), and tested for reducibility. Manganese sulfate and chloride were unsatisfactory additives causing cracking and degradation of the pellets during reduction. Manganese dioxide, carbonate, and the ores were satisfactory additives. The additives increased pellet compression strengths with a corresponding loss of reducibility, as compared with the pellets without manganese additions. The changes in compression strengths and reducibility were caused by the formation of jacobsite spinel and slag within the pellets. However, when the induration temperature was lowered from 1,300 deg to 1,200 deg c the reducibility and compression strengths were comparable with the pellets without manganese additions indurated at 1,300 deg c.