Providing meaningful incentives demonstrates to respondents that researchers understand the competing demands on their time and value their input. The effects of incentives, particularly when prepaid, are strongly established in survey research literature as effective tools for increasing response. However, effectiveness of incentives on web-administered surveys is less clear, and can be impacted by a number of factors, including incentive type and amount, timing, and mode of survey administration. This paper seeks to contribute to research on incentives for web-based surveys by examining the effects of the following: This paper uses data collected during the first wave of a nationally-representative survey of public school principals designed to take place across three waves of data collection. To determine a maximally-effective incentive strategy for subsequent years, we embedded an experiment into the study using electronic gift cards. All sample members were eligible for a standard $50 post-response incentive, but were also randomly assigned to one of four experimental conditions: (1) an additional $50 incentive for completing early in the field period, (2) a $25 incentive prepaid with the initial survey mailing, (3) a $25 prepaid incentive used during nonresponse follow-up, and (4) the standard $50 post response incentive, which serves as the control group for this experiment.