This article examines whether online and mail surveys produce convergent results, which would allow them to be used in mixed-mode service quality studies. In the context of a large business-to-business service quality assessment, an analysis of the accuracy and completeness of respondent answers to both open and closed questions suggests that online and mail surveys produce equivalent results. Composite reliability shows consistently high levels for both groups, and the means and variance-covariance matrices are equal across modes. However, minor differences occur between the two survey methods; online respondents provide more improvement suggestions, indicate more often to which competitor they want to switch, and provide lengthier answers in response to requests for examples of positive experiences with the company. This research provides important findings regarding the process for, and results of, comparing two survey modes.