This paper shows that while telephone polls produce answers that are similar to those obtained from large-scale random surveys there are some sharp differences in results obtained online. The paper shows that these differences cannot be removed by weighting by demographics, newspaper readership or by using attitudinal variables. The research does, however, uncover evidence of significant and disturbing mode effects. In particular, a growing band of professional online panel members seem to race through online surveys, giving responses that explain a good measure of the differences between online and telephone research. These findings suggest that the online research industry needs to devise methods to ensure online respondents carefully consider the answers they give, and design questions and answer codes that do not inadvertently lead online respondents to certain answers.