Mutual cooperation between general and specialty contractors for win-win business has recently risen as a buzz word in Korea construction industry. For sustainable mutual cooperation, it is critical to achieve a better understanding of the extent to which general and specialty contractors share critical factors of mutual cooperation. The objective of this study is to identify and discuss key characteristics of perceptions towards mutual cooperation between general and specialty contractors. Key factors for mutual cooperation were identified through a questionnaire survey and statistical tests, and consensus or disagreement as to critical factors of mutual cooperation were identified and discussed.