Unrecognised deterioration in hospitalised children may lead to adverse events such as unplanned admission to intensive care, cardiac arrest and death. Identifying deterioration in children is complex due to child-related, physiological and system-related factors. Paediatric Early Warning Scores (PEWS) have been proposed as a mechanism to support clinicians in recognising clinical deterioration. This chapter offers a practice-based approach to PEWS. You will learn about the functions and features associated with PEWS and the types of PEWS in use. The factors that contribute to the challenge of recognising deterioration in children and why we might need a PEWS will be discussed. An overview of the evidence for PEWS will follow, together with guidance on how you might assess the quality of a PEWS. The role of PEWS within the wider system will be presented before we take a look at the potential future developments for PEWS. The chapter will conclude with some practical tips for clinicians in using PEWS.