This paper presents an investigation of lexical first language (L1) attrition, asking how a decrease in lexical accessibility manifests itself in long-term residents in a second language (L2) environment. We question the measures typically used in attrition studies (formal tasks and type–token ratios) and argue for an in-depth analysis of free spoken data, including factors such as lexical frequency and distributional measures. The study is based on controlled, elicited and free data from two populations of attriters of L1 German (L2 Dutch and English) and a control population (n = 53 in each group). Group comparisons and a Discriminant Analysis show that lexical diversity, sophistication and the distribution of items across the text in free speech are better predictors of group membership than formal tasks or elicited narratives. Extralinguistic factors, such as frequency of exposure and use or length of residence, have no predictive power for our results.