Inclusion Criteria:

• Able to perform reproducible spirometry according to American Thoracic Society (ATS) criteria

• History of asthma symptoms that are adequately controlled in the 4 weeks prior to study entry, and meets at least one of the following criteria:

  1. History of mild persistent asthma symptoms (on average greater than 2 days per week with symptoms or albuterol use for symptoms or greater than 2 night-time awakenings per month during the year prior to study entry) and has been treated with a single-controller ICS dose less than or equal to 160 mcg per day of a beclomethasone-equivalent or a LTRA (in an age-appropriate dose) for the 4 weeks prior to study entry; individuals treated with a combination controller therapy (e.g. ICS+LTRA or ICS+LABA) in the past 8 weeks will not be eligible
  2. Not currently being treated with ICS, a history of mild persistent asthma, and 1 to 2 exacerbations in the year prior to study entry (but none in the 3 months prior to study entry)
• FEV1 reversibility of greater than or equal to 12% following bronchodilator administration (4 puffs); individuals who do not meet this requirement may qualify for enrollment if their PC20 methacholine FEV1 is less than or equal to 12.5 mg/ml
• History of clinical varicella or varicella vaccine; individuals needing the vaccine may receive it from their primary care physician prior to study entry
• Ability of parent to provide informed consent; verbal assent must be obtained from children less than 7 years of age and written assent must be obtained from children between 7 and 18 years of age
• If female, willing to use an effective form of contraception

Participants will be eligible for the 44 weeks of treatment if, after the 4-week screening period, their asthma remains controlled, and they demonstrate at least 80% predicted pre-bronchodilator FEV1. Participants must meet ALL of the criteria stated below during the 8-week screening period to continue in the study:

• Meets the definition of acceptable asthma control, which is NOT having one or more of the following during ANY 2-week period:

  1. On average, on more than 2 days per week, experiences one or more of the following:

     1. Diary-reported symptoms
     2. The use of inhaled bronchodilator (not including pre-exercise)
     3. Peak flows in the yellow zone (less than 80% of personal best defined as based on PEF value obtained at study visit 1
  2. More than 1 night-time awakening due to asthma
• Demonstrates adherence with taking study medications (at least 75% of scheduled doses), rescue medications (using both rescue inhalers for at least 75% of rescue doses), and completing patient diaries (at least 75% of days)
• Pre-bronchodilator FEV1 greater than or equal to 80% predicted at study visits 2 and 3
• Agrees to not use a spacer with beclomethasone/placebo study and rescue medications

NOTE: In January 2008, the Data and Safety Monitoring Board (DSMB) approved changes in the TREXA eligibility criteria, by which neither FEV1 reversibility ≥ 12% nor a participant's methacholine PC20 ≤ 12.5 mg/ml were required for randomization.

Exclusion Criteria:

• Corticosteroid treatment for any condition prior to study entry within the following defined timepoints:

  1. Oral - Use within 2-week period of the screening visit
  2. Injectable - Use within 2-week period of the screening visit
  3. Nasal corticosteroids may be used at any time during the study at the discretion of the study investigator or primary care physician
• Current or prior use of medications known to significantly interact with corticosteroid disposition (within a 2-week period of study visit 1), including but not limited to carbamazepine, erythromycin or other macrolide antibiotics, phenobarbital, phenytoin, rifampin, or ketoconazole
• Pre-bronchodilator FEV1 less than 60% predicted at study visit 1
• Any hospitalization for asthma in the year prior to study entry
• Presence of chronic or active lung disease other than asthma
• Significant medical illness other than asthma, including thyroid disease, diabetes mellitus, Cushing's disease, Addison's disease, hepatic disease, or concurrent medical problems that could require oral corticosteroids during the study
• History of cataracts, glaucoma, or any other medical disorder associated with an adverse effect to corticosteroids
• Any asthma exacerbation in the past 3 months or more than 2 in the past year.
• History of a life-threatening asthma exacerbation requiring intubation, mechanical ventilation, or resulting in a hypoxic seizure
• History of adverse reactions to ICS preparations or any of its ingredients
• Receiving hyposensitization therapy other than an established maintenance regimen (continuous regimen for at least 3 months)
• Pregnant or breastfeeding
• Cigarette smoking or smokeless tobacco use in the year prior to study entry
• Refusal to consent to a genotype evaluation
• Current participation or participation within 1 month of study entry in another investigational drug trial
• Evidence that the family may be unreliable or nonadherent, or may move from the clinical center area before study completion