The linkages of achievement-related boredom with students' appraisals and performance outcomes were examined in a series of 5 exploratory, cross-sectional, and predictive investigations. Studies 1 and 2 assessed students' boredom in a single achievement episode (i.e., state achievement boredom); Studies 3, 4, and 5 focused on their habitual boredom (i.e., trait achievement boredom). Samples consisted of university students from two different cultural contexts (North America and Germany). In line with hypotheses derived from Pekrun's (2006) control-value theory of achievement emotions, achievement-related subjective control and value negatively predicted boredom. In turn, boredom related positively to attention problems and negatively to intrinsic motivation, effort, use of elaboration strategies, self-regulation, and subsequent academic performance. Findings were consistent across different constructs (state vs. trait achievement boredom), methodologies (qualitative, cross-sectional, and predictive), and cultural contexts. The research is discussed with regard to the underdeveloped literature on achievement emotions (Contains 4 tables and 1 figure.)