What we know: Asthma is a disease of mucosal and immunological development. If a child's first episode of wheeze occurs in the first year of life, the child has about a 50% chance of developing asthma. If a child develops recurrent wheeze, the probability that it is related to asthma rises to about 80%. The presence of atopy, positive allergen skin-prick tests or elevated IgE antibody levels increases the probability of asthma to over 95%. Evidence of changes in lung function or of inflammation confirms a diagnosis of asthma. What we need to know: Can an algorithm be created for general practitioners to predict the likelihood of the development of asthma on the basis of presenting symptoms and relevant investigations? Is it feasible to use regular lung function testing or induced sputum samples to monitor the development of asthma in early childhood? How can we better understand in-utero programming for asthma? What characteristics of airway mucosal maturation are associated with the development of asthma? What deviations from normal immunological development are associated with the development of asthma?