The aim of this study is to contribute to a better understanding of challenges and factors which influence learning efficiency with electronic-portfolios. Based on the "Technology Acceptance Model" (TAM; Davis, Bagozzi, & Warshaw, 1989) we analyzed "external variables" (e.g., computer-anxiety) that influence technology acceptance and the "actual system use" in form of self-regulated learning. Additionally we included computer related attitudes and correlated them with external variables as well as measures of self-regulated learning. To foster learning efficacy with electronic portfolios the program Microsoft OneNote was used. A group of N = 32 preservice teachers worked on an electronic-portfolio in OneNote for 14 weeks. Results showed that computer-anxiety and the challenge of working with an electronic portfolio decreased over time. The more the computer was rated as a useful tool for learning and teaching, the less computer-anxiety, the more challenge and interest and better mood students reported. In contrast the more the computer was seen as uninfluential tool for working and learning, the more computer anxiety, hopelessness, anxiety and less positive mood, interest and joy to work on the electronic-portfolio has been reported. So, students' computer related attitudes should be considered when working with an electronic-portfolio to better tailor instruction to learner needs.