Background Readmission rates after major procedures are used to benchmark quality of care. We sought to identify readmission diagnoses and factors associated with readmission in patients undergoing pulmonary lobectomy. Methods Analyzing the State Inpatient Databases (Healthcare Cost and Utilization Project), we reviewed all lobectomies performed from 2009 to 2011 in California, Florida, and New York. The group was subdivided into open (OL) versus minimally invasive lobectomy (MIL; thoracoscopic/robotic). We used unique identifiers to determine 30- and 90-day readmission rates and diagnoses and performed regression analysis to determine factors associated with readmission. Results A total of 22,647 lobectomies were identified (58.8% OL vs 41.2% MIL; median age, 68 years; median length of stay, 6 days). Most patients (59.8%) had routine discharge home (home health care, 29.4%; transfer to other facility, 8.8%; mortality, 1.9%). The 30-day readmission rate was 11.5% (OL 12.0% vs MIL 10.8%, p = 0.01), while the 90-day readmission rate was 19.8% (OL 21.1% vs MIL 17.9%, p < 0.001). The most common readmission diagnoses were pulmonary (24.1%), cardiovascular (16.3%), and complications related to surgical/medical procedures (15.1%). Preoperative factors associated with readmission included male gender (odds ratio, 1.19), Medicaid payer (odds ratio, 1.29), and several individual comorbidities. Surgical approach and postoperative complications were not independently associated with readmission. Conclusions Readmission is a frequent event after pulmonary lobectomy and is strongly associated with preoperative demographic factors and comorbidities. Resources and services should be directed to patients at risk for readmission and multicomponent care pathways developed that may circumvent the need for repeat hospitalization.