“It’s a dangerous business, Frodo, going out your door. You step onto the road, and if you don’t keep your feet, there’s no knowing where you might be swept off to.” Written by J.R.R. Tolkien in The Lord of the Rings over a half-century ago, these words catch the mindset of the short-term international travel phenomenon that has likely swept a congregation, high school, or college campus near you.

This travel comes by different names: service trips, short-term missions, immersion trips, alternative spring breaks, and social justice delegations. If you have known a teenager or college-aged student in the last twenty years, then you may have encountered trip fund-raising, heard personal stories of transformation, or seen photos of their travels to foreign lands.

Social scientists have been relatively late to this (travelling) party. This past month, an article by two co-authors and myself in the Journal for the Scientific Study of Religion analyzed these trips and the state of current research. What do we know about this phenomenon?

First, international travel is a major spiritual practice, particularly for youth, which has flown under the radar. Robert Wuthnow shed the first systematic light on this in his book, Boundless Faith. In 2005 over 2% of American adult attendees of religious worship had left the country on a church-affiliated trip in the previous year. About 16% of church-going adults reported going on such a trip at some point during their youth.  Among the youth of today, the rate of participation is much higher: about 29% of youth between the ages of 13 and 17 have been on such a trip. That’s a lot of teenagers!  And it illustrates that this is a practice of real importance for today’s adolescents.

Second, while this style of religious engagement does not belong to any one tradition, there are important differences among religious traditions that we can discover from the National Congregations Study. About 1/4 of American congregations have had a group that “traveled to another country to assist people in need” in the previous 12 months.  Catholic congregations are less likely to sponsor these trips than Conservative Protestant congregations—about 24% and 34%, respectively. If we consider only domestic rather than foreign trips, about 23% of Catholic congregations sponsor a domestic trip, a rate still much lower than the 37% of Liberal Protestant congregations and 36% of Conservative Protestant congregations. (And this is not just a Christian phenomenon—about 17% of non-Christian congregations sponsor domestic trips and 20% foreign trips.)

Third, such trips appear to make a difference for youth, both religiously and spiritually. Our recent article showed that, controlling for a host of other influences and in comparison to youth who did not go on such a trip, trip participation influenced volunteer work, political participation, and giving money to charity. For example, trip participants were twice as likely to do volunteer work. They were about 40% more likely to become involved in political activities. Two other scholars were able to show that participation on such a trip increases religious participation and strengthens religious beliefs about the character of God.

These recent research results are important and should be more widely known. Many participating congregations spend a large amount of staff time and money organizing such trips. So a lot of people want to know, is it worth the money and effort?  Previously, only anecdotal evidence for the success of such trips has been available, and a number of previous studies actually cast doubt on the ability of such trips to change participants in any meaningful way.  A few years ago Christianity Today had a lively debate about many of these issues.

So, yes, Tolkien’s insight about leaving home appears to be correct for short-term international immersion travel. But, lest we put all our resources into sending people outside our local congregational Shire, let me suggest a few caveats.

• It is unclear how these trips cause these changes. The encounter with different cultures and suffering may affect participants through new emotions. The intense interaction with pastoral leaders or activists might lead to new patterns of behavior. The development of a mini-community of support among participants might generate new expectations. A change in conceptions of God and Church could inspire different behavior.  Or, it could be a mix of all of these things.

• It is unclear for how long these changes exist. All the research so far has been over a short follow-up time period of only a few years.

• It is unclear what types of trip activity matters. One important thing to keep in mind is that what happens on these trips can vary drastically. Building a school building is different than evangelizing local schoolchildren, which is different than meeting with local leaders about the impacts of globalization on political and economic conditions. Another important aspect of these trips is each group’s “style.” Sometimes communities fail to coalesce; sometimes shared ignorance instead of discovery characterizes a group.

• Finally, it is unclear how these trips assist local communities. There is evidence that they create useful transnational ties, but also that they may undermine local economic patterns of self-sufficiency. This is one of the most important questions going forward in this area of research, one I’ll revisit in the future.

It can be a dangerous business going out the door. Transformation can happen, but like many things in the spiritual life, this is not guaranteed. And, as any good Tolkien fan knows, transformation makes returning home merely another stage in the journey.