In the U.S. Catholic Church, parish and diocesan mission partnerships have become a predominant mode of mission in the 21st century. Principle practitioners of this form of mission, mostly lay Catholics, have very little formation or foundational knowledge regarding cross-cultural mission. Institutionally, the official Catholic Church offers no formational guidance in the practice of this type of mission. The present study will explore ethical standards and formulate an appropriate set of ethical norms for mission partnership practices. These norms will be derived from a) official Catholic Social Teaching, b) the field of development ethics, and c) wisdom from experts in the field of mission partnerships. The study will elucidate current practices of sixty parish partnerships in four U.S. dioceses and evaluate them against the developed ethical norms. The study will identify factors that enhance or detract from the likelihood of meeting these ethical norms. The findings of this study will be presented at missiological conferences to advance dialogue regarding parish and diocesan partnerships: American Society of Missiologists, U.S. Catholic Mission Association, and the U.S. Conference of Catholic Bishops. The study will be a source for official Catholic guidance and direction for this new form of mission. Laterally, the study will serve as a point of dialogue with other mission sending denominations fostering inter-denominational discussions and providing a framework for further collaboration and dialogue.