In this study the effects of a remedial spelling training approach were evaluated, which systematically combines certain visualization and verbalization methods to foster students' spelling knowledge and strategy use. Several achievement and test anxiety data from three measurement times were analyzed. All students displayed severe spelling disorders at the beginning of the treatment. It was administered in single-case sessions and took about 80 hours. Empirical results could demonstrate statistically significant increases in students' general and error-specific spelling test performance, also reaching a considerable overall effect size. Furthermore, a statistically significant decrease in their spelling-specific test anxiety scores appeared at the end of the treatment. Finally, these findings were discussed in terms of conceptual and methodological issues concerning both the evaluation of remedial treatments in natural training settings and the need for evidence-based treatment practice. (Contains 6 figures and 1 table.)