This thesis determines the approximate size of the world’s intelligence industry in quantitative terms. It reviews existing literature which describes, in qualitative terms, various themes found about intelligence agencies around the world. The thesis provides a quantitative method to estimate unknown intelligence spending and personnel. The study concludes that the world’s intelligence industry spends approximately 106 billion United States Dollars, and employs about one million people. Furthermore, the hypothesized direct correlation between Gross Domestic Product (GDP) and intelligence spending may exist, but the research does not strongly support the assertion. It is apparent that GDP is a factor when it comes to intelligence spending, but it does not seem to be the primary component.