In a randomized test of mixed-mode data collection strategies, 386 participants in the Raising Healthy Children (RHC) Project were either (a) asked to complete a survey via the Internet and later offered the opportunity to complete the survey in person or (b) first offered an in-person survey, with the Web follow-up. The Web-first condition resulted in cost savings although the overall completion rates for the 2 conditions were similar. On average, in-person-first condition participants completed surveys earlier in the field period than Web-first condition participants. Based on intent-to-treat analyses, little evidence of condition effects on response bias, with respect to rates or levels of reported behavior, was found. (Contains 3 tables and 2 figures.)