Asthma is common in every pediatric practice, yet diagnosis still too often relies on symptoms alone. Spirometry adds objective evidence for safer decisions. This practical lecture is both for pediatricians already performing spirometry and for those considering introducing it. It covers equipment recommendations, reimbursement, test quality, bronchodilator reversibility and interpretation pitfalls. Participants should leave ready to measure rather than guess—and to interpret spirometry confidently in 2026.