The Higher Education Research Institute at UCLA has been studying the developments and patterns of spirituality and religiousness of college students since 2003.
A recent report indicates a pattern of spiritual growth among many students between their freshman and junior years of college: http://www.spirituality.ucla.edu/news/Spirituality_on_Campus_release_12.18.07.pdf
For additional information from the 5-year study, see http://www.spirituality.ucla.edu/news/index.html for news releases, and http://www.spirituality.ucla.edu/publications_reports/index.html for published journal articles.
