This degree project aims to investigate which methods five school teachers, in compulsory education, integrate into their practice when teaching ESL learners vocabulary through reading. Moreover, it aims to find out if the reported teacher practices reflect what is currently viewed as effective vocabulary instructions. The research question that guided this study was, what methods or underlying theories do ESL teachers, in South Sweden, find useful when teaching vocabulary through reading? The research used classroom observations, individual interviews, together with a thorough analysis of relevant research on the subject of SLA. Moreover, despite the vast research in this area regarding effective practices of vocabulary acquisition, teachers tend to use old fashioned, and simple methods when teaching and assessing vocabulary acquisition. Underlying reasoning is said to be lack of time, or knowledge of how to incorporate efficient practices in their teaching. To conclude, we believe that teachers would benefit from receiving further education on how to incorporate potent practices, so that they are able to more efficiently integrate them into their current language learning activities.