The incidence of serial non-participation and protest responses has largely been ignored in willingness to accept (WTA) applications. This paper analyses serial non-participation with a focus on choice experiment applications using a WTA format to investigate preferences of ecosystem services providers towards incentive-based schemes. The paper addresses two main objectives. First, a review of the literature on WTA for participation in incentive-based schemes is used to identify and discuss a range of possible motives for protest responses that emerge in a WTA context. Second, drawing on choice experiment data on olive farmers’ preferences for agri-environmental scheme participation in Southern Spain, we analyse the impact on WTA estimates of censoring serial non-participation resulting from protest or high compensation requirements (very high takers) from further analysis. Using a random parameter logit model in WTA space, we find that the inclusion or exclusion of serial non-participants in the analysis can have a significant impact on marginal and total WTA estimates. Based on the findings, the paper makes recommendations on how to minimise the incidence of protest responses through survey design, regarding the identification of protesters as opposed to very high takers, and regarding the treatment of both for WTA estimation.