This paper elaborates a coherent conceptual framework - a necessary step prior to

the development of specific theories and the deduction of hypotheses. Based on previous work on regime changes, it identifies what should be regarded central,

peripheral, and distinct regarding political regime and affiliated concepts and rejects

several alternative perspectives.

The paper suggests how we can systematize our research on regime changes

by distinguishing between different phases and outcomes. Institutional perspectives

that focus on both formal and informal institutions and that addresses the complex

connection between rules, behaviour and attitudes are found to be the most plausible.

The regime definition based on this insight points out four defining principles -

character of rulers, access to power, vertical power limitations, and horizontal power

limitations. Moreover, the political-institutional perspective put forward enables researchers to draw systematic distinctions between three crucial dimensions (the rule

dimension, the behavioural dimension, and the attitudinal dimension) as well as different phases (transition, installation, and operation) and outcomes of regime

changes.