ObjectiveTo evaluate the impact of introducing the Step-by-Step approach on care quality in young febrile infants.DesignObservational study including infants ≤90 days old with fever without source seen in a paediatric emergency department 5 years before (n=1222) and after (n=1151) its introduction. Quality of care was evaluated in terms of adherence to recommendations, resource use and safety.ResultsAdherence: percentages of infants undergoing both urine and blood tests and infants <15 days old receiving full sepsis evaluation increased (84.7% vs 91.0% and 23.9% vs 63.3%, respectively; p<0.01). Resource use: lumbar puncture and admission rates decreased (24.1% vs 18.7% and 43.6% vs 38.3%, respectively; p<0.01), while the rate of antibiotic therapy increased (30.2% vs 43.2%; p<0.01). Safety: the invasive bacterial infection rate among infants managed as outpatients was unchanged (0.7% vs 0.3%; p=0.24).ConclusionThe introduction of the Step-by-Step increased the quality of care provided to young febrile infants.