Experts predict that mobile Internet usage will overtake desktop Internet use worldwide by 2015 (mobi-Thinking 2014). With the rapid increase in use of mobile devices for Internet, web surveys completed using smartphones and tablets have followed suit, with current estimates ranging from 7% -30% of web surveys taken on a mobile device (Maritz 2013). Rather than being at the forefront in the conduct of mixed-mode web surveys, survey methodologists are playing catch-up as they learn to master these new survey development tools. This talk will: (1) provide an overview into the emerging empirical evidence of the implications of ignoring mode differences in the design of web survey on accuracy; (2) discuss the strengths and weaknesses of common strategies researchers employ for dealing with mobile responses; and (3) offer design tips for dual-mode (desktop and mobile) optimization of web surveys.