The present study focuses on teacher’s attitudes to the European Language Portfolio (ELP) in mother tongue English programs. More specifically it will explore how effective the ELP and portfolio assessment are in mother tongue teaching inSweden. The aim is also to assess whether mother tongue English students perform equally well in the four language skill areas. This case study seeks to find the strengths and weaknesses of the ELP according to the teachers that are using the ELP as an assessment tool, as well as investigating previous evaluation materials used to identify achievement in mother tongue. For this purpose, a case study was conducted using semi-structured interviews with four English mother tongue teachers at theLanguageCenterin Göteborg (henceforth LCG). The teachers interviewed at the language center use the ELP assessment but do not actively use the other parts of the language passport. The LCG materials for the mother tongue ELP were adapted from the original ELP 6 to 16 years created for Österåker municipality by Iakovos Demetriádes in 2007. Mother tongue teachers in Göteborg have since identified a number of the ELP’s strengths, as well as some of its weaknesses. The ELP is compatible with the Swedish syllabus, which makes it easier to write a written assessment for each class from the 1st grade and up.  There are however problems with individual teachers interpretation of ELP descriptors.  These problems will be brought to light later on in this paper.