Do centre-based early education programmes prepare children for starting school? We wanted to find out if attending a centre-based early education programme was better than: (a) not attending any programme; (b) receiving a standard pre-school programme; and (c) if there were any unwanted effects. We found 32 studies involving 16,899 children aged 3 to 7 years old. Four studies compared centre-based early education interventions with no treatment. Twenty-two trials compared an enriched school curriculum to treatment as usual. The largest study was in 3,726 children and the smallest study was in 59 children. Studies were conducted around the world, mostly in the USA (28 studies). Studies, on average, lasted for 12 months; the longest trial lasted 6 years. Centre-based early education programmes for improving school readiness probably make little to no difference to children receiving either no programme or a standard curriculum. This systematic review found very low, low and moderate certainty evidence that centre-based school readiness interventions or enriched school readiness interventions make little to no difference in school readiness outcomes. Interventions may convey marginal benefits for children who do not attend preschool or who receive a standard preschool generic curriculum on specific academic areas such as mathematics, reading and vocabulary but any gains were not sustained over the long-term. There were a lack of studies measuring school readiness, health development and physical development. No studies assessed adverse effects.