By definition, the cause of sudden infant death syndrome (SIDS) is not known. Observational studies have found an association between SIDS and several risk factors, including prone sleeping position, prenatal or postnatal exposure to tobacco smoke, soft sleeping surfaces, hyperthermia/overwrapping, bed sharing (particularly with mothers who smoke), lack of breastfeeding, and lack of soother use. The risk of SIDS is increased in families in which there has been a prior sudden infant death.We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to reduce the risk of SIDS? We searched: Medline, Embase, The Cochrane Library, and other important databases up to April 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found 28 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review, we present information relating to the effectiveness and safety of the following interventions: advice to avoid prone sleeping; advice to avoid tobacco-smoke exposure; advice to avoid soft sleeping surfaces; advice to avoid overheating or overwrapping; advice to avoid bed sharing; advice to breastfeed; advice to promote soother/pacifier use; and advice to promote room sharing (without bed sharing).