This chapter discusses metacognitive cross-linguistic awareness in language learning, with a focus on Norwegian advanced learners of English. It is argued that even quite proficient language learners can benefit from explicit knowledge of differences and similarities between their first language and their second one. This knowledge will increase the potential for positive transfer and help to prevent negative transfer. Three small-scale studies illustrate language contrasts and learner behaviour in the use of modal auxiliaries, modal combinations, and topic identifiers. A parallel corpus is consulted to uncover differences between English and Norwegian before corpora of Norwegian-produced L2 English and novice L1 English are explored to find out whether the cross-linguistic differences are reflected in the learner output. In a complementary investigation, a group of university students express their views on the value of L1/L2 comparisons in L2 learning. The predominant attitude is that knowledge of similarities and differences between the languages is beneficial, although linguistic self-consciousness and hypercorrection may also arise from such knowledge. It is suggested that the corpus techniques illustrated in the chapter may help teachers and learners notice relationships between the L1 and the L2, which in turn may foster cross-linguistic awareness and metacognition.