This is the Editorial to a Special Issue entitled “Cyanobacterial blooms. Ecology, prevention, mitigation and control”. The Special Issue is a product of a European COST Action, CYANOCOST. In this Special Issue, contributions describe methods currently available for the management of cyanobacterial blooms, a key issue threatening the ecological functioning of lakes and the ecosystem services they provide . Contributions start with a section on the prevention of blooms, through the restriction of nutrient availability for cyanobacterial development at three levels: (1) in the catchment, (2) at the inflow to the lake and (3) in-lake methods, including nutrient release from the sediment. Then follows a section on control of blooms where blooms could be formed in the lake, but the chosen treatment restricts cyanobacterial growth to a level where risks and negative effects are minimal, e.g., artificial mixing, flushing or biomanipulation. The Special Issue continues with contributions on mitigation where blooms do develop, but physical and chemical methods mitigate the negative effects. For effective control key traits of the dominant cyanobacteria, characteristics of the lake system and an adequate design of the control method must come together. Each contribution answers questions like: what is the proposed or proven working mechanism of a given method? What have been the successes and failures? What are the reasons for success or failure? How is success linked to characteristics of the waterbody being treated? The Special Issue is concluded with contributions aiming at social and political aspects of bloom management .