The purpose of this exploratory study was to examine the actions of online language learners from an activity theoretical perspective. It also attempted to explain how the students' learning outcomes evolved from their online learning experiences. This explanation placed an emphasis on the learners' previous experiences, defining their activity systems, the use of mediational tools, and the resolution of contradictions. Within this activity theoretical case study a background survey, four interviews, and three field observations were conducted with seven foreign language students of an online Spanish course. The students' on-screen actions were recorded and subsequently documented in a video episode log. This log, the background survey, and the interview transcripts were coded for the a priori categories established in the research questions and for emergent themes. Seven mediational tools were identified, including a widespread use of online dictionaries and translators. The students attempted to use the mediational tools to gain control over their online language learning; however, as exhibited by the students varying levels of regulation, some students were unable to reach or maintain self-regulation while using computer-based tools. In addition, the nature of the mediational tool use appeared to be influenced by the variety of linguistic backgrounds. Three levels of contradictions were identified including: conflicting-object contradictions, inter-activity contradictions, and technology-related contradictions. The findings of this study indicated that contradictions may be invisible to the subject of the activity. Furthermore, it was noted in this research that some students may have the capacity to identify the contradiction, yet they may not have the desire or motivation required to make the necessary change to further learning and development within the activity. Thus, contradictions may not always be resolved even when they are visible. [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.]