The goal of this chapter is to review the methodologies used to assess boredom. The most widely used methods are self-report measures in the context of experimental research and cross-sectional surveys. We expand upon previous reviews of dispositional and situational self-report measures of boredom by presenting the established as well as recently developed psychometric scales, which are used to assess trait and state boredom in general and in domain-specific contexts, such as education, work, or sports. Next to retrospective state scales, probe-caught methods are used in experimental boredom research. In these experiments, participants are tasked to report their levels of boredom when a probe interrupts their current task. The subjective nature of self-reported boredom has motivated researchers to combine these measures with behavioral, physiological, and neurological markers. In the last part of this chapter, we will review this work, which reports promising results and encourages further research to identify the measures that are sensitive to boredom. In this last part of the chapter, we will also explore objective methodologies for studying boredom that are mainly based on human–computer interaction research.