Article misuse and omission are common errors in article use in L2 English. A particularly influential theory concerned with article misuse is that of Ionin (2003aIonin ( , 2003b, whose basic assumption is that, in L2 acquisition, adult learners still have access to Universal Grammar. Central to her theory is the concept of the Article-Choice Parameter, which is set to either definiteness or specificity in article-based languages. According to Ionin's Fluctuation Hypothesis, speakers of a language without articles fluctuate between the two settings of this parameter and produce systematic errors in article choice. Speakers of an L1 with articles have been shown to transfer the parameter value from their L1 to L2 English. This paper tests the predictions made by Ionin's account, based on data from an empirical study with a group of German speakers and two groups of Russian speakers. One of the Russian groups had studied English for a longer period of time, and at university level, and also had knowledge of another L2 with articles besides English. The results from this study do not provide clear support for Ionin's account. The German group rarely misused articles, as predicted, but only one of the Russian groups showed fluctuation. The Russian group with fewer years of English study and generally no knowledge of another L2 with articles showed variable patterns of article misuse and also often omitted articles. An explanation of why the two Russian groups differed is proposed.