A core test of any international relations (IR) theory or model is how reality-inclusive it is. The impediments to getting such a theory or model right, however, are more than conceptual – the very language you use can act as blinders rather than a source of revelation. That is why beginning in the 1980s we saw social scientists and security analysts attempt, in earnest, to use complexity theory and chaos theory to tease out new, expanded meanings and insights in their fields. Although their attempts have perhaps yielded more useful metaphors than conceptual breakthroughs, the off-kilter perspectives provided by these theories continue to provide added value to researchers. To illustrate this point and provide added context for today’s lead article, the following primer looks at how complexity theory is helping us to define and analyze today’s IR environment effectively.