Ecological interface design (EID) is a candidate framework for designing interfaces for complex sociotechnical systems. Interfaces based on EID have been shown to lead to better performance than traditional interfaces, but not all participants benefit equally. Thus, it is important to identify ways of raising the performance of all participants using an EID interface. The purpose of this article is to determine whether encouraging participants to engage in self-explanations (i.e. reasoning aloud) can help them “make the most” of EID. An experiment was conducted using DURESS II, an interactive, thermal-hydraulic process control microworld with an interface designed according to the principles of EID. During this one-month study, participants controlled DURESS II under normal and fault conditions on a quasi-daily basis. Two experimental groups occasionally watched a replay of their own performance immediately after completing a trial, while the control group did not. In addition, the self-explanation (SE) group was instructed to explain aloud the reasons for their control actions while watching the replay. The replay group simple watched their trials again with no verbal explanation. The SE participants were divided into “good” and “poor” groups according to several performance criteria. An analysis of the protocols produced during self-explanation revealed that “good” SE participants showed more signs of self-explanation in their protocols than did the “poor” SE participants. There were no substantial differences between the SE, replay and control groups for normal trials. However, the SE participants did have the best overall performance on fault trials, suggesting that self-explanation can help operators make the most of EID.