This study assesses the reasons behind learner dropout in adult EFL environments. Differences between two groups -- dropouts (N=154) and persistent learners (N=106) -- are examined using a questionnaire with qualitative and quantitative components. The study focussed on three areas: characteristics of the two groups (such as age and proficiency), their attitudes (self-efficacy, attitude to the language), and dropouts' perceptions of their language-learning experience. Significant differences were found in age and proficiency, among others, as well as in attitudes to the teacher and the language. When degree of demotivation is considered, further differences arise in attitudes to the course and in learners' perceived need to learn English for work. Dropouts tend to retain negative views of their teacher and of the course, showing that in-class factors are powerful demotives in adult language learning. Demotivated learners tended to attribute dropout to external factors, commonly mentioning poor teaching practice, a lack of speaking practice, and a discrepancy between their desired level and their perceived 'stagnant' level. The findings from this study inform teacher and administrator attitudes and behaviour in FL academies, helping them to identify learners who may be susceptible to, or who have already started down, the path to dropout.