The purpose of this mixed-methods study was to understand the key constructs and processes underlying the mentoring relationships between doctoral students and their mentors. First, exploratory and confirmatory factor analyses were used to evaluate the measurement structure underlying the 34-item Ideal Mentor Scale (IMS; Rose, 2003), followed by an examination of factorial invariance and differences in latent means between graduate students differing by gender, age, and Master's vs. Doctoral status. The IMS was administered to 1,187 graduate students from various departments across the university at Arizona State University (ASU); this sample was split into two independent samples. Exploratory factory analysis on Sample 1 (N = 607) suggested a new four-factor mentoring model consisting of Affective Advocacy, Academic Guidance, Scholarly Example, and Personal Relationship. Subsequent confirmatory factor analysis on Sample 2 (N = 580) found that this four-factor solution was superior to the fit of a previously hypothesized three-factor model including Integrity, Guidance, and Relationship factors (Rose, 2003). Latent mean differences were evaluated for the four-factor model using structured means modeling. Results showed that females placed more value on factors relating to Affective Advocacy, Academic Guidance, and Scholarly Example, and less value on Personal Relationship than males. Students 30 and older placed less value on Scholarly Example and Personal Relationship than students under 30. There were no significant differences in means for graduate students pursuing a Master's versus a Doctoral degree. iii Further study qualitatively examined mentoring relationships between doctoral students and their faculty mentor using the Questionnaire on Supervisor Doctoral Student Interaction (QSDI) coupled with semi-structured interviews. Graduate support staff were interviewed to gather data on program characteristics and to provide additional context. Data were analyzed using Erickson's Modified Analytical Inductive method (Erickson, 1986). Findings showed that the doctoral students valued guidance, advocacy and constructive, timely feedback but realized the need to practice self-reliance to complete. Peer mentoring was important. Most of the participants valued a mentor's advocacy and longed to co-publish with their advisor. All students valued intellectual freedom, but wished for more direction to facilitate timelier completion of the degree. Development of the scholarly identity received little or no overt attention.