This study, aimed at supporting the work of assessing college students' spiritual formation in Christian higher education, looked at relevant empirical studies from psychology of religion and higher education student development. The review of the literature allowed the researcher to identify findings about college students' religiousness and spirituality (R/S), as well as methodological insights to inform assessment practice. Overall, college students tend to decrease in religious affiliation and participation, even though belief remains constant. The various factors that influence college students' R/S include gender, race/ethnicity, institutional affiliation, peer religiosity, and attachment to early caregivers (including parents). Due to the preponderance of factors that speak to the R/S, a spiritual development ecosystem model was proposed for assessment of college students' spiritual development. Such a model acknowledges the multidimensional nature of R/S as well as the pervasiveness of its influence on one's holistic development. Additionally, the distinction was made between assessment "of" spiritual formation and assessment "as" spiritual formation. While measuring college students' spiritual development is important to learning outcomes assessment in Christian higher education, inviting students to knowingly participate in assessment may serve as a spiritually formative act itself, a step in the assessment process that also functions as a learning experience. This mirrors the biblical concept of the Law (torah), which dually functions as content to be learned and a standard to be met. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]