Although software has been studied with technology adoption and training research, the study of specific software features for professional groups has been limited. To address this gap, I researched the impact of software features of varying complexity on internal audit (IA) professionals. Two studies along with the development of training materials were conducted to investigate the effect of software features on adoption and training in the IA profession. The first study emphasizes the development of a model for internal auditors, extended from the Technology Acceptance Model (TAM). This model was tested with a sample of 185 internal auditors. I found that organizational and individual factors affected the technology acceptance of internal auditors in the same ways as general users, but social factors did not have any influence on the technology acceptance of internal auditors differently from general users. I also tested system usage, perceived usefulness, and perceived ease of use with feature complexity and found that as feature complexity increases, perceived ease of use decreased so that system usage decreased. The results also indicated that perceived usefulness had more influence on technology acceptance when feature complexity was low, and perceived ease of use had more impact on feature acceptance when feature complexity was high. The second study is experimental research to test the effect of software training at the feature level. Training materials were developed for Benford's Law, an advanced software feature of generalized audit software (GAS). A training group, given Benford's Law training, was compared to a control group without training on beliefs, use, and performance. Through the analysis of 56 audit professionals, I found that software feature training increased the belief of using software features and the use of software features, but did not have an immediate effect on performance. Rather, auditors spent more time on practicing a newly trained software feature and extended the use of Benford's Law to other audit tasks. The additional analysis disclosed that the use of advanced software features had no effect on performance score yet increased performance time. In addition, feature beliefs were positively associated with software beliefs as expected. [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.]