 We will derive a multivariable logistic regression model for quantifying the likelihood that 30-day readmission is avoidable. The development sample will include all cause 30 days readmissions for adult patients hospitalized with CAP. The outcome of interest is a potentially avoidable readmission within 30 days of discharge. We will use medical record-abstracted data for both the index hospitalization and readmission. Candidate predictors will be identified by combining the findings from a systematic literature review with the opinions of field experts. 