Screening may bring benefits but also harm; just because it can be done does not mean that it should be done – and the same resources may be better used in other ways. Population screening should be done within an organized that includes certain core elements, from identifying target populations, through treatment, to monitoring and evaluation. There is no justification for unorganized screening. While it may seem simple, putting together a screening programme is a complex task and requires many things to work both inside and beyond the health system. Wilson & Jungner’s screening principles remain the gold standard when deciding on implementing, continuing or discontinuing screening programmes, although they often require expert judgement as well as high quality evidence, including consideration of resource implications, effectiveness and cost effectiveness, as well as adaptation to country context. Care is needed when deciding to implement a screening programme to protect against the potential for commercially driven vested interests and supplier-induced patient demand. It is essential that decisions to implement, continue, or discontinue screening programmes are made transparently, setting out clearly the arguments for and against. It is also important to identify barriers to maximizing the effectiveness of programmes and put in place measures to overcome them. Potential barriers may relate to health system structures, such as payment models and availability of human, physical and financial resources. Potential solutions include financing models that encourage appropriate use, improving information flows, ensuring health workers have appropriate skills, and removing logistical barriers.