The author identified and researched churches and para-church ministries with best practices and proven training resource materials to equip short-term mission (STM) trip team leaders and participants to have greater effectiveness in their STM trip endeavors with reliable principles. The first principle is that STM trip leaders must be well-equipped to train and lead their teams, and thus they will have a greater impact than their counterparts: untrained STM team leaders. The second principle is that once trained, STM trip leaders will know what to do purposely in order for them to have successful STM trips under all circumstances. The third principle is that once trained, STM trip leaders will strategically have systems in place to avoid or deal with pitfalls that tend to diminish the spiritual impact and the quality of STM trip experiences. The fourth principle is that once trained, STM trip leaders who are well equipped to train and lead their teams, become excep tionally indispensable catalysts to foster future long-term missionaries because of the quality of their previous STM trip experiences.The purpose of these case studies is to discover best practices and proven training resource materials to equip STM trip leaders and participants to have greater effectiveness and thus successful ministry in their STM trip endeavors by surveying three distinct ministries. In this project, STM trips will be defined by not only the length or duration of a specific mission trip, but also in terms of the specific ministry focus during the time frame which helps to determine its quality and effectiveness. Churches and para-church organizations will have a greater impact in their STM trips when the leaders of the teams and their participants are well trained for every assignment that encompasses their STM trips. The case study method was chosen. That allows an outside researcher flexibility to enter the context of interest, establish rapport, and to observe pertinent details and probe with formal and informal questions that will lead to deeper clarification and understanding in virtually every area of their inquiries. It also allows the researcher to administer data collection gathered from written materials as well as one-on-one interviews, in order to compare and contrast the findings. This project showed that STM trip leaders who are well equipped to train and lead their teams to have a greater impact than their counterpart, untrained STM team leaders. Also, after training STM trip leaders, they then know what to do in order to have successful STM trips under all circumstances. This research project showed there are churches and para-church ministry organizations with best training resource materials qualified to develop effective STM leaders and participants. When comparing the r esults of the three subjects in this research project, it is refreshing to discover the similarities in strong biblical convictions among them and the passionate commitment that fuels the fibers of their training resource materials to produce the kind of disciples that will glorify God on the mission field and at home.