Little is known about the strategies end-user programmers use in debugging their programs, and even less is known about gender differences that may exist in these strategies. Without this type of information, designers of end-user programming systems cannot know the "target" at which to aim, if they are to support male and female end-user programmers. We present a study investigating this issue. We asked end-user programmers to debug spreadsheets and to describe their debugging strategies. Using mixed methods, we analyzed their strategies and looked for relationships among participants' strategy choices, gender, and debugging success. Our results indicate that males and females debug in quite different ways, that opportunities for improving support for end-user debugging strategies for both genders are abundant, and that tools currently available to end-user debuggers may be especially deficient in supporting debugging strategies used by females.