This study empirically investigated the impact of an online learning community project on university students' motivation in learning Chinese as a foreign language (CFL). A newly-proposed L2 motivation theory - the L2 motivational self system (Dörnyei 2005; 2009) - was used as the theoretical framework for this study. The three aspects of motivation (ideal L2 self, ought-to L2 self, and L2 learning experience), as described in this theory, were measured before and after the online project. Specific motivating and demotivating features of the online project were generated from participants' responses. Four individuals with different heritage and technology backgrounds were selected as cases to provide information about their perception of this online project and the possible impact of this project on their motivation. A concurrent transformative mixed method design was employed to collect both quantitative and qualitative data. A pre- and post-test survey and semi-structured interviews served as the main instruments for data collection. Paired t-tests were conducted to identify differences in the participants' pre- and post- scores for the three aspects of motivation. Constant comparative method and double coding method were used to generate the major themes about the motivating and demotivating features of the online project. A narrative analysis approach was taken to explore how individuals with different backgrounds perceived their experience in this online project and the possible impact of the project on their motivation. The results indicated that there was a significant difference in L2 learning experience before and after the online project, while there was no significant difference in the other two aspects of motivation (ideal L2 self and ought-to L2 self). This finding provided empirical evidence about the different natures of the three motivational aspects. That is, ideal L2 self and ought-to L2 self were built up over a long period of time and thus relatively stable, while L2 learning experience was more dynamic and fluid and had a tendency to change even within a relatively short period of time. Regarding the motivating and demotivating features, the results suggested that the most motivating features of this online project were the access to alternative learning resources and tools and opportunities to connect to a larger community of Chinese learners, while the demotivating features were mostly related to the technology barrier and the time and effort it took to complete this project. Furthermore, findings from the interviews with the selected individuals implied that regardless of their different heritage and technology backgrounds, most of them had a positive experience of this online project. However, the impact of this project on their motivation was limited.