Information technology (IT) projects are considered successful if they are completed on time, within budget, and within scope. Even though, the required tools and methodologies are in place, IT projects continue to fail at a higher rate. Current literature lacks explanation for success within the stages of system development life-cycle (SDLC) such as (a) business, (b) functional, (c) development, (d) testing, (e) training and deployment, and (f) production support. This qualitative study had two purposes. The first was to explore and define criteria for measuring success during individual SDLC stages; the second was to determine effective managerial style that can have a positive influence on project success for various SDLC stages. Based on the theories of SDLC and IT project success, a Delphi study was conducted. The primary research questions addressed the measures of project success, manager's role, and managerial styles for each SDLC stage. The study was conducted with an expert panel of 18 project managers, 3 from each SDLC team. The panelists completed a Web-based survey developed from the literature and ranked the measures of project success, managerial styles, and roles. The responses were analyzed for identifying common factors, roles and styles; coded, reduced and tested for independence of teams using chi-square tests; and cronbach's alpha test was performed for reliability. The results indicated that democratic style was suited for testing and sustainment teams, coaching style for business and deployment teams, affiliative and authoritative styles for functional and development teams respectively. The implication for positive social change is greater IT project success because project managers will be able to align their management style with the SDLC team. [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.]