The stress patterns of Afrikaans and Dutch simplex words correspond to a large extent. However, a small percentage of words differ with regard to the placing of the main stress. The theoretical descriptions of this phenomenon in Afrikaans and Dutch are compared and the conclusion is reached that the Afrikaans description has a higher degree of descriptive and explanatory adequacy than its Dutch counterpart. This can be ascribed to a number of factors, some of which are dealt with in the article. It is furthermore demonstrated that the majority of shifts in stress patterns from Dutch to Afrikaans take place according to the main stress rule. This article indicates how these shifts provide strong support for the main stress rule for simplex words which forms the basis of the argument.