While the short-term missionaries' long-term impact on local communities is often unknown, Cano believes that the most tangible fruit of short-term mission trips is the dramatic impact the ministry has on the kids who go on the trips. Taking kids outside their cultural comfort zone almost always helps them grow in their faith. This reality motivates Cano to go to work every day.

"It's a high for me to see one kid, a missionary, take off from here and return completely changed because they see something they've never seen before," says Cano. "I can't get that anywhere else."

Sean Lambert works with Youth With A Mission in San Diego, CA and has been involved in short-term missions for 22 years. He estimates that his ministry has organized the construction of over 900 houses in Mexico. Lambert points to James 1:22 as a reason the trips have such an incredible impact on kids.

"It says don't be just a hearer of the word, but a doer," says Lambert. "When you hear the word of God and do it, you grow. It creates an appetite for discipleship. Bang for the buck, youth guys say it's the best growth producer they do all year…. It creates a disciple rather than someone who's just trying to get through life and not fall into hell."

A Fundamental Change in Missions Philosophy
Representatives from all three of these short-term mission agencies said that the life change of the students who go on the trips is a high motivation for taking the trips. But this emphasis on using mission trips to grow and develop the missionary is a drastic divergence from past mission paradigms. Most mission paradigms were based on the Great Commission—the goal being to spread the Gospel to others, not use an overseas experience to grow personally and become better disciples ourselves. Effective discipleship calls for prioritizing culturally appropriate methods of ministry, often requiring long-term missionaries to sacrifice themselves in order to minister within the context of the culture.

When short-term missions are primarily focused on the growth of the missionary, the typical result is ministry that isn't effective over the long term.

"People who go [on short-term trips] get an experience. It benefits them," says Dr. Jehu Hanciles, a native of Sierra Leone and professor at Fuller's School of World Mission. "…But there's very little you can do as far as effective missionary enterprise in that short of time."

This may be the first missions movement in church history that's largely based on the needs of the missionary.

"That says something about our therapeutic culture," says Lingenfelter. "Our culture focuses a lot on the healing of ourselves, as opposed to the healing of others. I guess too much self-reflection ultimately takes us in a direction different from the challenge that Jesus gives us—to take up our crosses and follow him."

In addition to short-term missions' tendency toward self-focus, short-term trips, even multiple trips, don't necessarily enhance true cross-cultural understanding. Lingenfelter says that a short-term missionary never goes through what missiologists call a paradigm shift. Thus cross-cultural situations continue to be interpreted through the missionary's own cultural framework, instead of the missionary learning over time to identify with another framework.

"To go through a process to change that [framework] just can't be done on a short-term trip," says Lingenfelter. "It takes learning language, living with people…. The fact of short-term missions is that, however long you're there, you never have to change the way you do your work."

Short-term mission trip leaders who've never gone through this cultural paradigm shift need to be humble and cautious about their level of cultural understanding, lest they lead trips that are irrelevant to the mission field.

Lambert says he's seen his share of short-term mission trips that lacked cultural understanding: "I talked to the director of World Vision in Mexico City and he said, 'My church gets painted once a year whether it needs it or not.'…Sometimes a youth leader will say to me, 'My junior highers want to paint,' and that's the fourth time a particular fence has been painted. But Mexican culture is very affirming, so they won't say anything."