There is ongoing debate in preservice science teacher education about the function, definition and assessment of preservice science teacher dispositions in preservice science teacher education programs. This is due to the numerous definitions found in the educational literature on teacher disposition. Previous research indicates that teacher dispositions are examined through the lens of teacher capacity and linked with knowledge and skills. Drawing on Schwab's (1976) definition of disposition, which includes the components of ability and desire, the aim of this study was to look at ability and desire through a pedagogical lens to conceptualize, define, and observe how ability and desire worked together and changed over time during a master of education and licensure preservice science teacher program. This two-phase phenomenological study took place during the preservice science teacher methods coursework and student teaching component of the master of education and licensure program. In phase one, the methods course instructor and co-developer of the program, who was presupposed to have high ability and desire was used to conceptualize the characteristics and definitions of pedagogical ability and pedagogical desire. In phase two, using the working definitions and characteristics of pedagogical ability and pedagogical desire, four preservice science teachers in the master of education and licensure program were interviewed about their experiences with lesson planning and student teaching. Using data from the preservice science teacher participants, patterns emerged that suggests that the characteristics of pedagogical ability and pedagogical desire are present in the preservice participants and that growth was similar among all preservice science teacher participants. The findings from the study illustrate how the characteristics of pedagogical ability and pedagogical ability work together and grow over time. The findings provide support that the right learning environment is important in the development of dispositions. Further, the findings support the concept that dispositions can be learned and grow over time. This information can be useful when designing preservice science teacher education programs, and assessing preservice science teachers. [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.]