Lexical acquisition often occurs through reading, yet little research has compared how cognates, false cognates, and noncognates are learned contextually through reading. To this end, we conducted a week-long pretest-training-posttest study with 54 adult Polish learners of English. During three sessions on consecutive days, participants read 45 short stories (170–317 words) containing 90 target keywords (30 cognates, 30 noncognates, 30 false cognates). We examined how word type, context informativeness, and number of keywords occurrences affected keyword learning. Additionally, participants were randomly assigned to a control or awareness-raising group, the latter trained to notice cross-linguistic similarities. Mixed-effects models showed learning of all word types at immediate posttest, with cognates being learned the most and false cognates the least. Higher context informativeness and more keyword occurrences improved learning for all keywords, but false cognates benefited the most from contextual clues. However, raising awareness of cross-linguistic similarity did not enhance contextual learning.