This publication, Army Regulation AR 15-6 Procedures for Administrative Investigations and Boards of Officers April 2016, establishes procedures for conducting preliminary inquiries, administrative investigations, and boards of officers when such procedures are not established by other regulations or directives. Even when not specifically made applicable, this regulation may be used as a general guide for investigations or boards authorized by another regulation or directive. There are three types of fact-finding or evidence-gathering procedures under this regulation: preliminary inquiries, administrative investigations, and boards of officers. Proceedings conducted pursuant to chapter 4 are preliminary inquiries. Proceedings involving a single investigating officer (IO), with or without assistance from assistant IOs, that use the informal procedures delineated in chapters 5 and 6, as applicable, are designated administrative investigations. Proceedings involving one or more IOs that use the formal procedures delineated in chapter 7 are designated a board of officers.