This article first presents a definition of context effects that eliminates from consideration factors beyond the control of survey researchers yet is sufficiently broad to incorporate diverse but related sources of survey context. It then examines four types of context effects that have been documented in mail and telephone surveys with an eye towards identifying new concerns which have arisen or may arise as a result of conducting Internet surveys. The four sources of context effects discussed are: the survey mode used to pose questions to respondents, the order in which questions are asked, the ordering of response options, and the choice of response scale. In addition to reviewing previous research, the results of new context experiments are reported in which response scales across Internet and telephone modes are manipulated.