Agile Information Systems Development Methods have emerged in the past decade as an alternative manner of managing the work and delivery of information systems development teams, with a large number of organizations reporting the adoption & use of agile methods. The practitioners of these methods make broad claims as to the benefits of their use. However, to date, only a few of these claims have been tested in the research literature. Agile methods, including Extreme Programming, Scrum, and others, prescribe very different practices, some of which are contradictory. Additionally, the use of the practices of agile methods is not restricted to agile development projects, and has been observed in non-agile methods environments. Even so, the previous research literature has usually focused on practices prescribed by a particular agile method. So what is different about agile methods, and what is the appropriate lens through which to study them? This dissertation finds that the most distinctive element of agile methods is their strong emphasis on obtaining and processing feedback from the environment. This dissertation evaluates the impacts of agile methods as indicated by the use of these feedback processes. In this study, the theoretical lenses of team adaptation, organizational learning, and the prior literature on new product development are used to explain the importance of a team's ability to process repeated and continuous feedback from the environment. We motivate hypotheses regarding the positive impact of agile methodology use on a multi-dimensional construct representing project success. This construct encompasses the quality of the delivered product, the benefits of the project to the organization, and impacts on project management outcomes. In addition, the nature of moderating influences of uncertainty on project success is discussed. The research design for the study utilized a survey that collected responses from 83 agile development teams. Generalized linear modeling was used to test four hypotheses regarding the impact of the extent of agile methodology use on project success, and the moderating influences of uncertainty. It was found that agile methodology use positively impacts project success, while structural complexity negatively moderates the impact of agile use. It was also found that environmental dynamism positively moderated the impacts of agile methods on project success. Discussion of the results is provided. [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.]