This thesis investigates the interaction between teaching and learning of English in young learners in Sweden and in Vietnam. It thus brings together two perspectives – teaching and learning – that are seldom compared between cultural contexts. The main focus of the study is to examine procedural and declarative knowledge of English grammar. A number of Grade 5 English lessons in primary school classrooms in Sweden (N=5 lessons in 2 schools) and Vietnam (N=6 lessons in 3 schools) were observed and analysed using the communicative orientation of language teaching (COLT) observation scheme (Spada & Fröhlich, 1995). The pupils’ proficiency in English (Grade 5; Aged 11–12; N=32, Sweden and N=44, Vietnam) was assessed using elicitation instruments that captured procedural and declarative knowledge of English subject–verb agreement. In addition to these measures, the children’s out-of-school exposure to English was examined in a questionnaire in which the children answered questions about their activities in and experiences with English outside school. The results show that teaching methodologies in Sweden and Vietnam differed. Swedish classrooms were more communicatively oriented, as has been suggested previously (e.g. Lundahl, 2012). In contrast, the Vietnamese classrooms were more grammar-oriented, a result in line with previous research (e.g. Khuong, 2015). The difference found in the teaching practices in the classrooms is paralleled by a difference in the learner outcomes as measured in the elicitation instruments. The learners in Sweden had a higher level of procedural knowledge as compared to the learners in Vietnam whereas the learners in Vietnam had a higher level of declarative knowledge as compared to the learners in Sweden. Analysis of the learners’ grammatical knowledge showed that most of the Swedish learners were able to produce 3-sg-s, but could not describe the rule (cf. Malmberg et al., 2000; Källkvist & Petersson, 2006). The opposite result was found among the Vietnamese learners, who were often able to give the rule but did not produce 3-sg-s. Thus, no correlation was found between procedural and declarative knowledge, in line with what has been suggested in earlier research (R. Ellis, 2008; Macrory & Stone, 2000; Seliger, 1979). An additional finding is that the Swedish learners, in addition to communicating more in the classroom, also had more exposure to English outside the classroom. The Vietnamese learners, on the other hand, had limited exposure to English outside school, except in the form of private tutors, and received more focus-on-form instruction in the classroom. The finding that the procedural and declarative knowledge of the learners was not correlated has implications for language teaching, and the results of this thesis may contribute to a better understanding of the L2 acquisition of grammar.