'Joined-up government' (JUG) approaches have emerged in many industrialized countries as a means to tackle persistent 'wicked' public and social policy problems (Pollit). Despite this, limited evidence exists concerning their implementation or effectiveness. 'JUG' was popularized by the Blair Government (UK) with its focus on addressing social exclusion. Following in these footsteps, in 2007 the Australian Government launched the Social Inclusion Agenda: a joined-up approach to improving the wellbeing of all Australians and addressing disadvantage. This paper focuses on findings from a study that examined the SIA as a natural experiment in JUG. Drawing on the implementation experiences of federal policy makers, our findings lend weight to emerging research into JUG that suggests that compatibility and consistency between goals, instruments, and processes is critical to success. We argue that closer attention needs to be given to developing 'supportive architecture' around joined-up initiatives to facilitate implementation.