Book excerpt: This book represents a comprehensive review of the most recent developments in paediatric pulmonary function testing and their clinical applications in common paediatric respiratory disorders. The first section reviews the current lung function tests used in infants and toddlers who are by nature unable to cooperate with most testing procedures. It describes the methodologies, provides normal values where available, and gives advice for data interpretation. The second section deals with the classic adult-type pulmonary function tests and their application in the semi-cooperative or cooperative.