Numerous scholars have pointed to positive associations between student perceptions of instructor credibility and student outcomes (i.e., cognitive learning, higher motivation, and increased willingness to participate in and out of class); however, their work has primarily considered traditional-aged students in the traditional classroom setting. Given the significant growth in distance education enrollments at post-secondary institutions across the United States (U.S.), the lens through which instructor credibility has traditionally been examined is broadened by this study. Drawing upon the work of McCroskey and Teven (1999), this mixed-methods research study explored the relationship between best online instructional practices and undergraduate student perceptions of instructor credibility as defined on three dimensions: competence, caring, and trustworthiness. Emphasis was placed on the six best online instructional practices that McCollum & Abdul-Hamid (2011) determined to be associated with student success (higher pass rates and lower withdrawal rates). Based on data obtained from an online survey instrument in which 67 responses were collected from undergraduate students (82 percent adults, 47 percent minorities, and 70 percent female) enrolled in multiple sections of a fully online upper-level course from within the communication field of study along with data from 16 synchronous online interviews, it was concluded that there is a significant and positive relationship between four of the six best online instructional practices ("continuous involvement and feedback from faculty (immediacy/presence)," "incorporate learning modules (targeted and logically placed)," "draw from experiences and introduce students to cultures and subcultures to add relevance," and "provide opportunities for collaborative learning") and student perceptions of instructor credibility on at least one of three dimensions of credibility. The best online instructional practice of "continuous involvement and feedback from faculty (immediacy/presence)," however, proved to be most meaningful with respect to student perceptions of instructor credibility, as the relationship between the two were consistently strongest across all three dimensions (competence, caring, and trustworthiness). [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.]