The purpose of this study was to assess the affective barriers to student achievement in developmental mathematics classes. A Delphi process was used to identify and corroborate a list of affective domain concerns that act as barriers to achievement for developmental students and developmental mathematics instructors. The process consisted of multiple rounds of questionnaires that elicited the opinions of a panel of developmental mathematics instructors in community colleges throughout Texas to seek consensus on their ideas of affective barriers to student achievement in developmental mathematics classes. Through the Delphi process, the perceived importance of the concerns identified by developmental mathematics instructors regarding affective barriers to students' success was determined. The study defined and ranked a group of 266 affective domain issues that exemplified the characteristics of a successful developmental mathematics instructor, the social and emotional needs that should be met to maximize the success of a developmental mathematics student, the components of a successful learning environment for a developmental mathematics classroom, and the content of the instructional design of a developmental mathematics course to maximize the success rate of the students. The median count of the final survey round revealed that 249 (93.6%) of the 266 items had a median greater than 2.0 and were considered to be of a high level of importance by the panel members. Based on these findings, some of the major conclusions of the study were that developmental mathematics instructors should consider affective domain qualities as the most important qualities in a successful developmental mathematics instructor, they should be responsible for meeting the majority of the social and emotional classroom needs of their students, they should understand that they are the most important factor of the successful learning environment in the classroom, and they should include engaging activities in their instructional design. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]