After finishing missionary training in the US, James and Diane partnered in the tribal church planting effort in Colombia by caring for the children of missionaries at the MK school. They had been serving there for 10 years, when an attack by rebel soldiers changed the face of what US citizens could do in Colombia.
Holding the missionary team at gunpoint, the rebels told James and another missionary that they would be taken hostage. Upon seeing that Diane was pregnant, the rebels released James and took another co-worker in his place. (The rebels later killed both kidnapped missionaries, Tim VanDyke and Steve Welsh.)
The Gleaves moved to the city of Bogotá and continued to serve for two more years, until the majority of US NTM missionaries were pulled out of Colombia due to security concerns.
Changing ministries, the Gleaves worked with counseling and helping college-aged missionary children who are in the U.S. without their parents. Now they serve in the St Louis, Missouri, area as missionary representatives for New Tribes Mission.
Speaking in churches and colleges, they seek to inform Christians in the Midwest about the needs and opportunities in missions. Their focus is mobilizing Christians to get involved in reaching unreached people groups with the Gospel. They have been members of New Tribes Mission since 1984.