This article presents the essentials of a successful counterinsurgency strategy by applying a technique known as systems thinking. (1) The fundamentals of good strategic thought lie both in recognizing the most significant interactions between different players, how they influence each other in unexpected ways, and how to measure progress in achieving the ends of the strategy. Systems thinking has proven successful in other contexts at explaining human behavior, policy choices, unintended consequences, and the resistance of systems to change. It also offers insight into how to assess one of the most difficult questions related to strategy in complex environments--how to know when the strategy has been successful. A strategist encounters many difficulties in developing and implementing a counterinsurgency strategy. One major impediment is the lack of a clear and simple way to describe the strategy--US military forces and senior policymakers have traditionally shown a need to learn and re-learn the basic tenets of counterinsurgency strategies. Another difficulty is determining appropriate measures of success, as the twists and turns of a counterinsurgent campaign often lead to considerable ambiguity regarding progress in relationship to the ultimate goal. Issues like these are not unique to counterinsurgencies. Systems thinking has proven useful in understanding public management and policy, energy and the environment, and theory development in the natural and social sciences. Many of these have something in common with insurgencies--complex actors and non-linear relationships, difficulty in measurement, band-aid solutions, impatience with results and unintended consequences or side effects. Systems thinking can provide intuitive and counterintuitive insights for understanding counterinsurgencies. While counterinsurgent theorists will encounter much that looks like old wine in a new bottle, several advantages accrue from developing and defending a counterinsurgency strategy through the lens of systems thinking, including an approach for gauging progress. Four different models of an insurgency will be introduced. Each model extends the previous one, providing new insight about the dynamics of counterinsurgent operations. In addition to unveiling the strategic imperatives for a counterinsurgent, the models also suggest a new way to organize measures of progress in a counterinsurgent campaign. First, however, a short introduction is needed to explain basic systems thinking. Systems Thinking All systems thinking models rely on two feedback loops--balancing and reinforcing loops. A reinforcing loop describes systems where elements reinforce one another, creating either a virtuous or a vicious cycle (Figure 1). [FIGURE 1 OMITTED] For example, in a bank account, as principal increases, it generates more interest, which in turn adds to the original principal, which in turn leads to even more interest, and so on. A snowball rolling down a hill symbol in the center denotes a reinforcing loop, to remind readers that there is an exponentially growing cycle. Reinforcing loops have inherent limits to growth, usually because one of the elements interacts with another loop to eventually slow growth. The other key feedback loop is called a loop. A balancing loop describes efforts to solve a problem or close a gap between a desired state and a current state (Figure 2). [FIGURE 2 OMITTED] The balancing loop is read from bottom to top in the order of the arrows: an action is taken to increase a current state. The + sign indicates an increasing relationship. This results in some closing of the gap with the desired state (the minus sign indicates an inverse relationship between elements). As the gap grows smaller, it adds to the desire for action, but it adds less and less as the gap shrinks, causing a slowing change in the current state, until the gap reaches zero, and no further action is required. …