Research into language learning demotivation has tended to focus on the identification of discrete factors resulting in demotivation. In this article, we report an investigation into the interrelationship among factors eventually leading to demotivation using a sequential exploratory mixed-methods design. In Study 1, 13 participants were interviewed about their demotivation experiences and what factors, they perceived, had led to demotivation over a period of 12 months. We then used these results to formulate a demotivation model. In Study 2, we tested the generalizability of this model on a larger sample (N = 2044). Using structural equation modeling, our results showed that the model fit the data, and most of its paths were statistically significant. This model showed that having a fixed mindset had one direct and two indirect paths to demotivation. The two indirect paths were through lowering the learner's ideal L2 self and through feeling disappointed by setbacks. We discuss the implication of our findings for language learning and teaching.