One of topicalities in the field of education in the 21st century is a necessity to share responsibility. Namely, students should learn to be more responsible for how and what they learn, whereas teachers should learn to share the ownership of the learning process with students, letting them be more involved in it as decision-makers. One way how teachers can encourage students become more conscious of the learning process is to engage them in self-assessment of their learning and learning outcomes. One of self-assessment tools in language education is the European Language Portfolio (the ELP). Apart from different ELPs for adults, there is a portfolio for students in Latvia: My Language Portfolio – The European Language Portfolio for young learners (age 7–12) in the paperback and digital versions. In the present study, the researchers explore how self-assessment can be incorporated in the English language lessons by offering self-assessment activities and the ELP to Grade 6 students to work on their reading skills. Reading skills make the basis for every person’s literacy as reading does not only concern reading itself, it is also about being able to master general knowledge of any other school subject and the world knowledge in general. Thus, the aim of the research is to find out how self-assessment can be used to improve reading skills in English in Grade 6. A case study was carried out for one month in one primary school in Riga, the research sample being two separate groups of Grade 6 students, in total – 26. The researchers analysed and interpreted data collected from assessment and self-assessment of reading activities, questionnaires filled out by students. The main findings of the research show that self-assessment can successfully be incorporated in lessons of English of Grade 6 students as it increases students’ motivation to learn and their reading skills improve. That could be based on the fact that self-assessment allows students to take more ownership of their learning process and learning outcomes, that way making students become more responsible. However, overall progress is not immense and for students who are more competent in English, improvement of their reading skills can barely be traced. It has to be highlighted that students, whose confidence in their English reading skills is lower, benefit from self-assessment more. It could be explained by students’ conscious work on particular problems with reading in English they discover while completing self-assessment activities.