This chapter’s focus on speakers of a non-English L1 provides an important perspective to the volume as a whole. It addresses three Spanish processes that can cause difficulty for L1 German learners through a discussion of collected data: spirantization, nasal place assimilation, and resyllabification. After laying out details on monolingual and bilingual language acquisition, as well as the age of onset of acquisition, the authors of the chapter motivate their study through a summary of some key differences between the sound systems of German and Spanish, including the processes of interest. The authors then describe their own study on bilingual phonology, which helps motivate the final stages of the chapter, where they propose pedagogical interventions to work on both perception (emphasizing sensitization to differences) and production (inspired by the Verbo-tonal approach).