A short-term mission (STM) is the mobilization of a Christian missionary for a short period of time ranging from days to a year; many short-term missions are called mission trips. The short-term missionary is a fairly recent innovation in the global missions movement, but many short-term missions agencies are seeing an increased number of trips that consist of a week up to a year.

Short term missions started in the 1960s. A few organizations, like YWAM (Youth with a Mission) and OM (Operation Mobilisation) created trips lasting from a month to a year. Short term missions was known as a way for young people to grow their faith and self, while also aiding those in need. Many individual churches joined in on the movement.

Then within the 1970s, high school students began to take part. It grew during the 1980s and was extremely popular in the 1990s. Short-term missions have had different meanings based on the people taking part. Some make it about looking for possible long-term missionaries and helping those who are already involved, where others focus on the spiritual path and growth while helping others. The idea that they are about serving others and growing in faith became the more popular reason to go on a mission trip. More than 2 million American's participate in these trips yearly. These trips act as a way for numerous people to help the less fortunate. While they are a way to grow spiritually, these trips also act as community service projects.

Generally, missionaries have been people sent to spread their religious faith, usually among the people of another country or region in which that faith is not widely practiced. In the past 50 years, churches have moved toward mobilizing young people for short-term trips.

There are independent Short-term Missions Organizations (STMs) as well as denominations and individual churches that facilitate these trips all over the world. Many individuals going on short-term mission trips raise partial or full support from family and friends to help pay for their trip. Costs include not only travel, food and lodging but often associated project expenses as well. In recent years, a number of services like have been established to help individuals raise support for their short-term mission trips using online email and social media tools.