This dissertation utilized critical incidents methodology to examine participants' endorsement of twelve primary growth factors during a Master's level group counseling class. Additionally, the study examined whether some factors are more salient than others at each stage of development (i.e., forming, storming, norming, performing) as defined by Tuckman (1965). Although the counseling field has placed considerable emphasis on the importance of personal growth and awareness in the training of mental health professionals (Council for the Accreditation of Counseling and Related Educational Programs [CACREP], 2009), the counselor education literature remains heavily reliant on theory and anecdotal evidence to explain issues that influence trainees' personal growth and awareness. The experiential group training has received wide acceptance as one of the effective means of facilitating the personal growth and awareness of trainees (Kline et al., 1997; Lennie, 2007; Merta, Johnson, & McNeil, 1995; Osborn et al. 2003; Payne, 1999; Yalom & Leszcz, 2005). However, there is much little research identifying the specific factors that are helpful in promoting the personal growth and awareness of student participants. Further, few of the available empirical studies have used a group development perspective in their investigation of such factors. The participants in this study were 27 students enrolled in master's-level group work courses and four group facilitators at three CACREP-accredited counseling programs in the northeastern United States. Each student participant completed a weekly journal entry, termed critical incident questionnaire, over the course of the semester; while group facilitators completed a group development checklist following each group session. Critical incidents were then analyzed and coded by growth factor. Identified growth factors were then examined for their relative salience during the four stages of group development outlined in Tuckman's (1965) model. Results indicated that the twelve growth factors accounted for 86% of the total number of critical incidents that participants reported as influencing their personal growth and awareness during the group experience. Two other factors, Outside Dynamics (OD) and Regular Attendance and Active Participation (RA), emerged and formed a secondary factors category, accounting for 100% of all the critical incidents. Tuckman's (1965) proposed stages of forming, storming, norming, and performing and the sequential nature of his model were partially supported. Results also showed that participants' endorsement of growth factors varied across stages of group development. The relative salience of growth factors varied as a function of both stage of development and time in the group. Within the forming stage, both Universality and facilitator Interventions emerged as the most salient factors. Vicarious Modeling and Dealing with Conflict were the two most salient factors during the storming stage. Within the norming stage, Cohesiveness/Bonding and Genuineness/Authenticity were the most salient factors. Self-Disclosure and Validation/Acceptance were the most salient factors during the performing stage. Implications for training and future research on growth factors in experiential groups in relation to group development are discussed. [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/en-US/products/dissertations/individuals.shtml.]