According to The Simple View of Reading, both decoding and linguistic comprehension processes are needed for reading comprehension for L1 as well as L2 students. Previous research has shown that early support is important for students who struggle with reading. The thesis aims to investigate the role of decoding and comprehension for students learning to read in Swedish as L2 and how teaching and early special support can promote reading development. The first study in the thesis has a cross-sectional design and examines scores on decoding, vocabulary, and reading comprehension. The results showed that L2 students in grades 1-3 in Sweden had significantly weaker scores on all three tests than L1 students and that both decoding and vocabulary are related to reading comprehension. The results also showed that a significantly higher proprtion of L2 students were in need of extra support in reading. The second study is a systematic scoping review that identifies findings from reading intervention studies of L2 students. The results showed that additional small group or within-class programs can support L2 students when teaching is matched to their individual needs. The study also supported the view that instruction in skills in one language can transfer to skills in another. The third study has a between-groups design and investigates the impact of a Response to Intervention (RTI) model with a focus on decoding. The results showed that the RTI model had the potential to promote both L1 and L2 student's reading ability but to a lesser extent among L2 students. The forth study has a single subject design and examines the impact of a systematic word decoding intervention in Swedish for students learning Swedish as L2. All students improved their word decoding ability. In conclusion, it can be seen that differentiated balanced reading instruction and early support in an inclusive setting can promote reading ability in students learning Swedish as a second language. A second language perspective in early reading education is discussed.