1	The Governmental Process David B. Truman Interest group refers to any group that, on the basis of one or more shared attitudes, makes certain claims upon other groups in the society for the establishment, maintenance, or enhancement of forms of behavior that are implied by the shared attitudes
2	Potential Interest Groups Definition of the interest group in this fashion . . . permits the identification of various potential as well as existing interest groups. That is, it invites examination of an interest whether or not it is found at the moment as one of the characteristics of a particular organized group. Although no group that makes claims upon other groups in society will be found without an interest or interests, it is possible to examine interests that are not at a particular point in time the basis of interactions among individuals, but that may become such. . .
3	What Interest Group Theory "Leaves Out" It is usually argued that any attempt at the interpretation of politics in terms of group patterns inevitably "leaves something out" or "destroys something essential" about the processes of "our"government. On closer examination, we find this argument suggesting that two "things" are certain to be ignored: the individual, and a sort of totally inclusive unity designated by such terms as "society" and " the state."
4	Interest Groups and the Nature of the State Men, wherever they are observed, are creatures participating in those established patterns of interaction that we call groups Many interest groups, probably an increasing proportion in the United States, are politicized. That is, either from the outset or from time to time in the course of their development they make their claims through or upon the institutions of government. Both the forms and functions of government in turn are a reflection of the activities and claims of such groups.
5	Institutions of Government Reflect Interest Groups The institutions of government are centers of interest-based power; their connections with interest groups may be latent or overt and their activities range in political character from the routinized and widely accepted to the unstable and highly controversial.
6	Seeking Access In order to make claims, political interest groups will seek access to the key points of decision within these institutions. Such points are scattered throughout the structure, including not only the formally established branches of government but also the political parties in their various forms and the relationships between governmental units and other interest groups
7	Multiple Access Points Enhance Interest Group Power A characteristic feature of the governmental system in the United States is that it contains a multiplicity of points of access. The federal system establishes decentralized and more or less independent centers of power, vantage points from which to secure privileged access to the national government.
8	Decentralized and Undisciplined Parties Enhance Group Power Both a sign and a cause of the strength of the constituent units in the federal scheme is the peculiar character of our party system, which has strengthened parochial relationships, especially those of national legislators. National parties, and to a lesser degree those in the states, tend to be poorly cohesive leagues of locally based organizations rather than unified and inclusive structures.
9	Variety of Access Points The variety of these points of access is further supported by relationships stemming from the constitutional doctrine of separation of powers, from related checks and balances, and at the state and local level from the common practice of choosing an array of executive officials by popular election.
10	Lack of Unified Executive At the federal level the formal simplicity of the executive branch has been complicated by a Supreme Court decision that has placed a number of administrative agencies beyond the removal power of the President. The position of these units, however, differs only in degree from that of many that are constitutionally within the Executive Branch. In consequence of alternative lines of access available through the legislature and the Executive and of divided channels for the control of administrative policy, many nominally executive agencies are at various times virtually independent of the Chief Executive.