Background: We used two principles of implicit learning, variability and complexity, to train mental orthographic representations in refugee English learners to improve spelling. Methods: Twenty-eight refugees enrolled in a 10-week English class were trained on classroom words using stimuli designed to encourage implicit learning. We contrasted high-variability visual input combined with either high-linguistic or low-linguistic complexity, using a short (<5 minute) PowerPoint-based training. Participants were regularly tested on their spelling and were compared with themselves using single subject design. Individual effect sizes were aggregated across participants, and we used dependent measures t-tests to compare conditions. Results: Participants learned significantly more treated words than control words in the high-variability/low-complexity condition, but not in the high-variability/high-complexity condition. Conclusions: Refugees can benefit from interventions designed to promote implicit learning but can be overwhelmed by too much input.