Effective Information Technology (IT) leadership is critical for achieving a good alignment between business needs and IT means of an organization. In the public sector, IT leadership is increasingly realized through the Government Chief Information Officer (GCIO) function, typically established by governments based on local circumstances and emerging needs. This makes peer-learning about the working of such systems and their transfer between different government contexts challenging. To address this concern, the authors introduced earlier a GCIO System - a set of inter-related activities to guide governments in gradually establishing, operating and sustaining the GCIO function. Based on a common conceptual model of the GCIO function, this paper defines a methodology for conducting the readiness assessment part of the GCIO System. The methodology comprises a set of assessment areas and a step-wise process to conduct assessment in these areas. The paper also shares the experience in applying this methodology in practice, and proposes how the assessment could inform the execution of other activities of the GCIO System.