In many compulsory second language (L2) classrooms, learners routinely encounter linguistically difficult L2 reading tasks. However, it is unclear (1) how learners behaviorally engage and perform on such tasks, (2) what motivational characteristics predict their reactions, and (3) whether maladaptive learner reactions can be ameliorated. This study examined the role of two motivational constructs (attributions and self-efficacy) and a common teaching practice (effort feedback) in predicting and ameliorating learners’ behavioral engagement and performance on linguistically difficult L2 reading tasks. Japanese high school students ( N = 238) studying English were recruited for an experimental study and randomly assigned to either the treatment group ( n = 124) or the comparison group ( n = 114). Both groups first performed a linguistically difficult L2 reading task. Time on task was measured as a direct indicator of behavioral task engagement. They then rated the success or failure attributions of their task performance. Next, the treatment group received brief positive feedback highlighting effort attributions (i.e. effort feedback), while the comparison group did not receive any attributional feedback. Both groups then rated their levels of self-efficacy to perform a similar task. Lastly, both groups performed a follow-up linguistically difficult L2 reading task, and their time on task was recorded. Results showed that participants generally displayed low behavioral engagement and performed poorly on the initial task. Both the treatment and comparison groups experienced a significant decline in their behavioral engagement in the subsequent task, but the treatment group showed a small improvement in their subsequent task performance. The external controllability dimension of attributions positively predicted learners’ behavioral engagement on the subsequent task. These findings shed light on an unexplored territory of task engagement research that warrants further attention.