Greg and Dawn, after graduating with a degree in Intercultural Studies, began their ministry with the mission in Latin America in 1977. After studying Spanish and serving for a year at the support center, they began their ministry with the Yanomami people group.

The Yanomami people live deep in the Amazon Rainforest with little or no contact with the outside world. After learning the language of the Yanomamis, the Sanfords carried on a church planting ministry for 12 years.

Since 1991, Greg has served as a mission representative and conference speaker, sharing many of the couple's experiences among the Yanomami people. Along with his representation responsibilities, Greg serves as director of the Wayumi Program in central Pennsylvania. Greg has also traveled around the USA and to other parts of the world, giving seminars on Ethnos360's chronological teaching program to other mission organizations and Bible colleges.

The Sanfords have two daughters, one son and eleven grandchildren. Their oldest daughter, Tammy, and her husband, Jamie, are with Ethnos360 serving in South America, making her a third-generation missionary. Their son Lane, who also served as a third-generation missionary, and his wife, Karrie, served for years with Ethnos360 in Papua New Guinea, planting a church amongst the Siar people. Their youngest daughter, Wendy, married to Ben Hazen (son of missionary parents who served in Africa), now serve together in youth ministry at a church in central Pennsylvania.