Upon returning to the United States, the Fullers began a Christian ministry at Koinonia Farm building simple, decent houses for low-income families in their community using volunteer labor and donations, and requiring repayment only of the cost of the materials used. No interest was charged, as it is with traditional mortgages, and no profit was made. These same principles guided the Fullers in expanding this ministry, called Partnership Housing, into a larger scale ministry known as Habitat for Humanity International. That vision was expanded in 2005 in the founding of a new non-profit housing organization, The Fuller Center for Housing.