Collecting evaluations following a professional development workshop and similar events has become common practice for assessing workshop quality. However, these evaluation forms often do not reflect best practices in survey development and result in average ratings that are uniformly high and uninformative. The purpose of this study was to evaluate the effects of rating scales on workshop evaluations using an experimental design where participants were randomly assigned one of four evaluation forms with different rating scales following workshops. We found that using a typical "poor to excellent" scale yielded the highest average (most homogeneous) ratings while scales that were off-centered, with more positive than negative scale points (positively packed), yielded ratings with more variability. Recommendations for designing workshop evaluations are provided.