When digitalizing governmental services, many countries invest in new e-government portals. Estonia, for example, uses a one-stop portal, which allows centralized access to all provided governmental services. Germany, on the other hand, realizes integrated portals that link several separate portals on federal, state and municipal level. The governmental service provision is decentralized, but forwarding between different portals is established. These two portal types have different characteristics that result from their specific design. When administrations decide to plan and implement such portals, it is useful to adhere to success factors to ensure an effective development. This paper reviews academic literature on success factors for e-government initiatives. As different aspects might become more relevant for the different portal types, the importance of the success factors for each portal type is examined. This research helps administrations to focus on critical aspects of development according to the specific portal type.