The purpose of this paper is to undertake a meta-analysis of findings reported in existing research on adoption and diffusion of e-government. Usable data relating to e-government adoption research were collected from 112 papers out of 779 research articles identified from the ISI Web of Knowledge database and journals dedicated to electronic government research. The findings indicate that there are some variables such as: perceived ease of use, perceived usefulness, intention to use, attitude, satisfaction, actual use, subjective norm, and perceived behavioral control, which are common and drive the research from citizens as well as from employees’ perspective. The meta-analysis of the existing e-government adoption studies found that the majority of the construct relationships demonstrated the significant range of average summative correlation, and effect size, but the influence of ‘facilitating condition’, and ‘perceived risk’ on ‘intention to use’ and of ‘service quality’ on ‘satisfaction’ was found as non-significant. The broader analysis of the e-government adoption and diffusion research also reflects that although a large number of theories and theoretical constructs were borrowed from the reference disciplines, their utilization by e-government researchers appears to be largely random in approach. The paper also acknowledges the theoretical contributions, limitations and suggests further research directions.