External search has played a very critical role in a firm’s innovation process. As a cornerstone of open innovations’ success, the work of external search has been altered by the advancement in information technologies (ITs). Employees at different organizational levels can source external knowledge and share them with other employees with consummate ease and speed. However, the inclusion of more and different boundary spanners and broadened search domains pose new challenges to firms in managing their open search process. In this study, we attempt to address this under-studied phenomenon by conducting multiple case studies to build a deep understanding of the open search work. Drawing on the perspectives of upper echelon theory and organic/mechanistic organizational forms, we developed a theoretical exposition of open search work by 1) evaluating the impact of each open search pattern on efficient search outcomes; 2) understanding appropriate IT mechanisms for each identified pattern; and 3) unveiling the relationships of three open search patterns by considering the uncertainty as a unique trait of open innovation. Through this study, we seek to contribute to building a middle-range theory of open search by shedding light on the different patterns of open search and their varying impact on search outcomes. Our findings can also provide useful insights to firms’ managers to design their innovation units effectively to achieve optimal results.