This paper uses original survey data from the 2010 UK General Election to examine two central questions about e-participation: how people engaged with the online campaign; and whether any mobilization effects of e-campaigning activity can be detected in terms of increasing individuals’ likelihood of participating after the election. Following our previous work, were-test and confirm a measurement model of e-campaign activities. Through exploratory factor analyses, we identify our three dimensions of e-campaign participation: e-information, e-party and e-expressive. We then show how these activities differentially predict subsequent online political participation: e-donate, e-contact, e-petition and e-discuss. We do this using a panel study design that allows us to impose robust controls on pre-existing levels of political engagement. Our results show that for the most part levels of pre-election engagement in e-donating, e-contacting and e-petitioning explain much of the post-election commitment to do so, and that online campaign involvement does not add significantly to this intention. However we have found that use of the internet during the campaign to obtain information does appear to have a lasting effect on the likelihood of discussing politics, even when prior propensity toward discussion is controlled for. We have further observed a significant negative association between engagement in formal e-campaign activities (e-party) and a later proclivity to take part in a direct democracy initiative online (e-petition). Our findings are in line with a growing conclusion that the internet’s role in stimulating participation is likely to be more complex than a simple direct effect andsupport the claim for adopting a more nuanced approach to the analysis of the mobilization effects.