Open government data has become an important policy among the government administrations around the world. Similarly, in this global movement, both central and local governments of Taiwan have dedicated efforts and resources to establish open data infrastructure. Nevertheless, because of their respective information environments, agencies possess different capabilities of open data implementations, and different outcomes are achieved. Accordingly, this research adopts and refines an open data maturity model from the literature for the assessment purpose. A quantitative approach by using survey is employed to assess the current development and implementation of open data among Taiwan government agencies.