Many welfare service innovations are markedly systemic in their nature. It means that they emerge from complicated interplay between political, administrative, technological, institutional and legal issues. Presumably, the adoption of systemic innovation is a challenging project. The adoption process contains knowledge intensive activities in which the adopters evaluate the pros and cons of ... [Show full abstract] innovation and make decisions based on the assessments. The paper identifies four different knowledge problems arising during adoption process. 1) Uncertainty refers to a lack of information, 2) complexity arises from the intricacy and connectivity of the various elements, 3) ambiguity means the lack of interpretative knowledge and 4) equivocality stems from multiple and conflicting interpretations. The paper proposes and discusses the managerial implications these knowledge problems pose for stakeholders involved in systemic innovation in welfare services. The paper also presents the managerial implications for each type of knowledge problem; uncertainty can be reduced by developing organisational knowledge management capabilities; complexity can be simplified by increasing knowledge capacity and decomposing problems, ambiguity can be addressed by structuring the unknown into a frame of reference, and equivocality can be encountered by ensuring the responsiveness of interaction and polyphonic organization. The paper concludes that understanding underlying knowledge problems properly is important because misunderstandings can have a detrimental effect on adoption of systemic innovation.