This is a multi-center, randomized, double-blind, placebo-controlled, superiority clinical trial evaluating short course (5 day) vs. standard course (10 day) of oral beta-lactam antibiotic therapy (amoxicillin, amoxicillin-clavulanate, cefdinir) for treatment of CAP in children 6-71 months of age who have clinically improved prior to enrollment. The study will randomize approximately 400 enrolled subjects to one of the two study arms (approximately 200 children in each arm) in order to reach 360 subjects completing Outcome Assessment Visit 1. Subjects will be randomized (1:1) to receive either a standard course of the initially prescribed antibiotic (10 days) or a short course of the initially prescribed antibiotic (5 days) plus 5 days of matching placebo. The study will recruit potential subjects from children who are diagnosed with CAP and who are initiated on oral beta-lactam therapy by healthcare providers in EDs, outpatient clinics, and urgent care centers at the study sites. Day -5 is defined as the date on which oral beta-lactam therapy is initiated for a diagnosis of CAP. Potential subjects will be identified at any time following clinical diagnosis of pneumonia. These subjects will be assessed for eligibility and enrolled on Day -3 to -1 of their initially prescribed oral beta-lactam therapy. Subjects may also be enrolled on Day 1 (the first day of receipt of study agent) provided they have not yet received any doses of the healthcare provider-prescribed antibiotic therapy for that day. The Primary objective is to compare the composite overall outcome (Desirability of Outcome Ranking, DOOR) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visit #1 (Study Day 8 +/- 2 days). The Secondary objectives are: 1) To compare the composite overall outcome (DOOR) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visit #2 (Study Day 22 +/- 3 days); 2) To compare the resolution of symptoms (a component of DOOR) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visits #1 and #2; 3) To compare the clinical response (a component of DOOR) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visits #1 and #2; 4) To compare solicited events (a component of DOOR) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visits #1 and #2; 5) To compare medically attended visits to Emergency Departments (ED) or outpatient clinics, hospitalizations, surgical procedures, and receipt of non-study systemic antibiotics (components of the clinical response) among children 6-71 months of age with CAP assigned to a strategy of short course (5 days) vs standard course (10 days) outpatient beta-lactam therapy at Outcome Assessment Visits #1 and #2