Recent experimental research has shown that respondents to forced-choice questions endorse significantly more options than respondents to check-all questions. This research has challenged the common assumption that these two question formats can be used interchangeably but has been limited to comparisons within a single survey mode. In this paper we use data from a 2004 random sample survey of university students to compare the forced-choice and check-all question formats across web self-administered and telephone interviewer-administered surveys as they are commonly used in survey practice. We find that the within-mode question format effects revealed by previous research and reaffirmed in the current study appear to persist across modes as well; the telephone forced-choice format produces higher endorsement than the web check-all format. These results provide further support for the argument that the check-all and forced-choice question formats do not produce comparable results and are not interchangeable formats. Additional comparisons show that the forced-choice format performs similarly across telephone and web modes.