Questions regarding the most effective teaching modality in foreign language instruction remain especially important for adult educators, since adult students have conflicting demands on their time and need to see the value of training. This research was centered around three cohorts of students taking courses of English of the same content and volume from the same provider. The students were university faculty and thus, of comparable demographics, and the courses were funded by the university. Over several years, and as the result of COVID-related restrictions, the courses were delivered in face-to-face (F2F), online, and blended modalities incorporating flipped classroom in the latter two. The aim of the research was to investigate the impact of a course modality on the perceived teaching effectiveness of a language course for adults. A quasi-experiment was used as a type of sequential mixed method. Relative perceived effectiveness of each modality was drawn from a combination of student evaluation of teaching (SET) and semi-structured interviews with former students who acted as both alumni and experts in education. SET comparison revealed no significant differences in results among the three modalities while interviews indicated a preference for the blended learning. At the same time, SETs of fee-paying students with comparable demographics taking similar courses at the same institution and analyzed previously showed a distinctive preference for a blended approach. That might be due to the differences in resources these two groups invested in studies: time vs time and money. The results imply that adult language educators have the flexibility to choose a modality while ensuring teaching effectiveness.