Pico is an acronym that describes the elements of a well-formed clinical question to support evidence-based decision-making. The PICO question can be used to frame a search for evidence to manage a single patient, or may be used to describe the study of a clinical problem in a population. The structure includes:We start the PICO process with P, where it is helpful to describe a group with a similar problem and include important characteristics of the patient or patients. Next, I indicates what is done to the patient(s), and may include a medication or other treatment, a diagnostic test, or an exposure (for example, to a potential toxin). The C step should be specific and generally limited to one alternative choice. The final step, O, should specify the measurable results used to compare the intervention or exposure to its alternative. At times, a comparison may not be relevant.For example, a parent might ask whether a single shot of a steroid would work as well as 5 days of oral steroids for a young child sent home from the emergency department after an asthma exacerbation. The clinical question in “PICO format” would be: “Among young children with an acute asthma exacerbation (P), is a single dose of intramuscular dexamethasone (I) comparable to 5 days of oral prednisolone (C) for resolution of asthma symptoms (O)?”The elements of the PICO question can guide the search for relevant and useful information, not only from literature databases but also from clinical consultants.1 A good PICO question can also guide clinical research. Many clinical research studies are designed to answer just this sort of well-structured clinical question.Since 2008, each study in AAP Grand Rounds that addresses a clinical question has been accompanied by a PICO question, enabling readers to judge how well the investigators have answered these questions. The PICO format works best for questions about therapies or other interventions (things we do to patients) but can be modified slightly to describe diagnostic tests, prognoses, or studies about the possible causes of a problem, by substituting a test result or exposure to a risk factor for the “intervention” and presence or occurrence of the disease for the “outcome.”For example, for a question about a diagnostic test, the “outcome” will be the “gold standard” test: “Among children with suspected hypercalciuria, does the calcium-creatinine ratio accurately reflect 24-hour urinary calcium?” and for a question about harm, the “intervention” will be an exposure: “Among children with acute otitis media caused by Streptococcus pneumoniae, does exposure to PCV7 vaccine (vs no vaccination) result in a greater likelihood of antimicrobial-resistant organisms?” Some publications abstracted in AAP Grand Rounds do not attempt to answer a specific clinical question, but instead describe a population, summarize a clinical recommendation or discuss an important general issue, so these abstracts are not accompanied by PICO questions.PICO questions, when well framed, should enhance the value of AAP Grand Rounds by clarifying study questions.