Factors influencing the adoption of and business case for Cloud computing in the public sector Cloud adoption in the public sector is taking off slowly, which is perceived as a problem. Models of factors influencing cloud adoption are derived for better understanding using literature and results obtained via desk research and surveys by the Cloud for Europe project. We conclude that several factors require further research, such as the culture in countries, climate, legislation, economics and politics, IT staff shortage and feelings of uncertainty, fear and impatience. Adoption factors have impact on the business case for cloud computing. Hence a business case template to compare cloudscenarios with zero scenarios is developed. We recommend to use the risk-adjusted balance between benefits and costs to decide on cloud adoption instead of focussing only on the benefits of cloudcomputing. Although this makes the business case for adoption of cloud computing less favourable, it provides a more realistic picture leading to sustainable decisions on cloud adoption.