This study compares the usability of a general heuristic evaluation to that of a domain-specific heuristic evaluation focused on technical documentation. Eight technical writers used both heuristic evaluations to identify usability problems in an online help application. The validity of the usability problems they identified was ascertained by user testing. No significant difference was found in overall effectiveness or efficiency. However, writers indicated greater satisfaction with the general heuristic evaluation, while the domain-specific heuristic evaluation was more effective in some categories and showed greater inter-rater agreement. Results suggest that differences in effectiveness were related to the level of detail of the heuristics. This study therefore recommends the incorporation of more detailed heuristics into heuristic evaluations.