This paper will present results of a longitudinal research on the characteristics of parties’ and candidates’ websites in Australia, France, Germany, Italy, Spain, United Kingdom and United States from 2006 until 2010. The websites of 170 parties and presidential candidates were analyzed both during and between national election campaigns, for a total of 620 observations. Website features were studied through a standardized coding frame that includes 57 variables, partly derived from previous studies and partly devised to reflect recent technological changes. Based on a combination of factor analysis and meta-analysis of coding frames employed in seven earlier studies of party websites, variables were divided into three groups: information, participation and delivery. The distribution of variables shows that, while on average parties and candidates only offer half the functions included in the coding frame, they place equal weights on information and participation, rather than prioritizing the former over the latter as most research claims. In order to identify causal relationships behind political actors’ adoption of online tools, additive indices representing website information, participation and delivery were computed and used as dependent variables in multivariate regression models which included independent variables measuring various aspects of technological development, the socio-political environment and party internal variables. Findings show that, among system-level variables, technological development, timing, electoral system and voter turnout are significantly correlated with some or all the indices; among party-level variables, financial resources, the use of democratic practices for candidate selection and ideology are significantly correlated with the amount of features on parties’ and candidates’ websites. These results have significant implications for political communication and party competition and suggest important developments for future research.