Successful reading comprehension--especially in a second language (L2)--relies on the ability to monitor one's comprehension, that is, to notice comprehension breaks and make repairs. Comprehension monitoring may be limited given effortful word processing but may also be supported through active reading. The current study addresses to what extent word processing difficulty reduces adolescents' ability to monitor their comprehension in their L2, and whether readers can compensate limitations given sufficient executive control. We conducted an eye-tracking experiment in which 34 adolescent L2 learners (aged 13-17 years) read short expository texts containing two within-subject manipulations. First, comprehension monitoring was tested through inconsistencies, for example, when the topic changed from "Spanish" to "Russian" vis-à-vis consistent controls. Second, word processing difficulty was altered by inserting either shorter and higher-frequency words such as "want," or longer and lower-frequency words such as "prefer." We additionally measured participants' executive control. Outcome variables were reading times on the whole texts and the words manipulated for inconsistency and word processing difficulty. We found evidence of successful moment-to-moment monitoring, as visible in adolescents' increased rereading of inconsistent compared to consistent information. We also found that adolescents adapted their monitoring differently to word processing difficulty, depending on their executive control: while adolescents with weaker control reduced their monitoring given higher word processing difficulty, adolescents with stronger control monitored their comprehension more (instead of less) on difficult texts. These findings provide insights into how L2 comprehension monitoring arises in the interplay of lower-level processing load and active reading processes.