With documented benefits and recent public policies, health IT has received increasing attention in recent years. However, knowledge about Thailand's state of hospital IT adoption is lacking. The literature also identifies organizational management practices that are important to health IT implementation, but these factors are rarely included in quantitative analysis. Paucity of theoretical developments in the area also prevents a systematic approach to IT implementation. To describe the current state of IT adoption in Thai hospitals and test a proposed model of organizational IT adoption that includes facilitating management practices and important hospital characteristics, motivated in part by Paré and Sicotte (2001)'s IT sophistication framework with modifications, a nationwide mail survey was conducted in 1,302 hospitals in Thailand. Findings suggest that basic IT adoption in Thai hospitals has passed the tipping point. The utility of the proposed framework is demonstrated, as is the importance of identified facilitating IT management practices. The final model, named the Theory of Hospital Adoption of Information Systems (THAIS), should be investigated in future studies.