A theoretical model of the emergence of assimilation and contrast effects in part-whole question sequences is presented. When one specific question precedes a general question and the two are not assigned to the same conversational context, respondents use the information primed by the specific question to form the general judgment. This results in part-whole assimilation effects. If both questions are perceived as belonging to gether, however, conversational norms of nonredundancy prohibit the repeated use of information that has already been provided in response to the specific question when making the general judgment. Accordingly, respondents interpret the general question to refer to aspects other than the ones covered by the specific question. Contrast effects may emerge in that case under specified conditions. If several specific questions precede the general question, however, the general one is always interpreted as a request for a summary judgment. This results in assimilation effects, even under conditions that would foster contrast effects if only one specific question is asked. The model is supported by experimental data and provides a coherent account of apparently contradictory findings previously reported in the survey literature.