The three West-Germanic languages Dutch, Frisian and Afrikaans are so closely related that they can be expected to be mutually intelligible to a large extent. In the present investigation, we established the intelligibility of written Afrikaans and Frisian by Dutch-speaking subjects. It appeared that it is easier for speakers of Dutch to understand Afrikaans than Frisian. In order to explain the results, attitudes as well as linguistic distances were assessed. There was no evidence of a relationship between attitude and intelligibility. Three linguistic distances did show a relationship with reading comprehension, namely the number of non-cognates, the transparency of the lexical relatedness of cognates, and the Levenshtein distance, which calculates the similarity between the written forms of words.