About MLD Marine Leader Development (MLD) is a comprehensive approach to leadership development that seeks to foster development of all aspects of Marines’ personal and professional lives. It is neither a philosophy nor a program; rather, it is a framework to be used by Marines at all levels for themselves and subordinates. This framework is the six Functional Areas of Leadership Development: Fidelity, Fighter, Fitness, Family, Finance, and Future. By addressing each of these individual areas, MLD seeks to ensure the development of Marines – and thus a Corps – that is cohesive, tactically and technically proficient, guided by moral purpose, and able to execute the toughest challenges. MLD will be implemented in all Marine Corps commands, and will supersede the Marine Corps Mentoring Program (MCMP).