Networks, collaboration and partnerships between the government and community groups offer prospects for stronger governance and improved public value. Many authors have reported on processes that enhance the prospects for successful collaborations, especially in handling intractable issues, but few have examined the limits to partnerships. A simple theory of government (involving the efforts of "reasonable people") is devised to explore the issues in creating sustainable partnerships. A graphical presentation is used to demonstrate that successful partnerships rely on more than good management; their success also depends on their effects on the rest of the polity, and the response to those effects. These processes limit the potential for partnerships to offer a general solution to problems of governance. Three conditions for sustainable partnerships are derived; benefit, support and acceptability. Attention to good network management, political risks and sound public administration can improve the prospects for a successful and sustainable partnership, but eventually (like other forms of human endeavour) there are limits to partnerships.