This study aimed to examine the frequent use of intra-sentential and inter-sentential code-switching during classroom interactions among Swedish-speaking students. The focus of this research also aimed to examine the motives as to why Swedish-speaking students code-switch during their English lessons and what word classes are affected by code-switching the most. The study took place in an upper secondary school and the English levels 5, 6, and 7 were observed during their open discussions and presentations. A total of 74 students participated in this study, where 15 participated in a semi-structured interview to share their thoughts on code-switching and their backgrounds, and 47 students participated in a survey anonymously. The results demonstrated that most students code-switch within sentences rather than between sentences. Most students demonstrated that they felt nervous and stressed when speaking in English due to their limited vocabulary skills in the spoken language, which resulted in them code-switching to Swedish.