Abstract   This intervention study examines effects on the decoding ability by one-to-one tutoring with adult illiterate second language learners of Swedish, in comparison to ordinary classroom education. In addition, the study aims to examine the participants’ experience of the intervention. Four illiterate pupils from SFI, Swedish language education for adult immigrants, were pretested and matched two by two. One of each pair participated in the intervention (30 minutes, four times a week during six weeks). The other two attended the ordinary classroom activities. Pre- and posttests showed that the test group managed to read more words per minute, improved their knowledge of Swedish graphemes and their reading fluency compared to the control group. The intervention even enabled one participant to reach the alphabetic stage in decoding, which the matched control person did not do. The experience of the one-to-one tutoring was mostly positive, and the illiterates were grateful for the intensive training.