Purpose: The purpose of this qualitative study was to identify and describe the most important factors that motivate or deter teachers in deciding to take on the informal or formal role of teacher-leader in Riverside County elementary school districts. Methodology: Endemic of a Delphi method, the instruments used within this study collected data from an expert panel of elementary school teacher leaders from Riverside County, California through electronic surveys in a four-round process. The expert panel consisted of teacher leaders in formal and informal roles as selected by elementary site administrators using criteria established by the researcher. The researcher collected data and tabulated frequency distribution, percentages of participant responses on the level of importance, median scores, and factors reaching 70% consensus. Findings: The research data showed that increasing student achievement, making a difference, creating a collaborative community, being informed, and informing others are the most important factors motivating teachers in deciding to become a teacher leader in a formal or an informal role. Additionally, making decisions was important in a formal role, and recognition and respect were important in an informal role. The most important deterrents for a formal and an informal teacher leader role were lack of time, lack of support, lack of direction or goal, and increased responsibility. Another deterrent in a formal role was fear; for an informal role, it was not having enough pay. Conclusions: These findings support the need to build a collaborative culture of authentic decision-makers through distributive leadership. The lack of time, support, and direction that teachers experience must be addressed by building teacher-leadership capacity. Implications for Action: Districts should train teachers in the Teacher Leadership Model Standards, provide teacher pre-service coursework in leadership skills and distributed leadership, train or hire administrators and teachers who support an authentic collaborative leadership culture, recognize and monopolize individual's areas of expertise, re-examine job titles, change the traditional school calendar, create or change support personnel positions to be housed at the site level where teacher leaders can support teachers on-site. [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.]