Statistical examinations of deterministic and stochastic response propensity assert that a sample case’s propensity is determined by fixed respondent characteristics. The perspective of this article, that of dynamic response propensities, differs, viewing sample cases’ propensities as evolving over the course of the data collection. Each sample case begins the data collection period in a “base” response propensity. Each change in the data collection protocol which the survey organization subsequently makes might change that base propensity. This article examines four questions: (1) Is there any evidence that the average response propensities of sampled individuals vary over the data collection? (2) Is there any evidence that propensities are influenced in accordance with specific actions taken by the survey recruitment protocol? (3) Do these changes have fixed effects or do they also vary across sample units or across the data collection period? (4) Does the change in propensities coincide with changes in nonresponse bias of key survey estimates?