This chapter focuses on the function, origination, and typical measurement and discussion of implicit bias. A brief overview of the neurological roots of implicit bias is explored as an evolutionary tool for quicker processing and decision-making – especially when cognitive load is high. Subsequently, sources of bias are explored. Finally, major methods of measuring implicit bias are discussed with a focus on understanding what each tool measures. Together, these forces, sources, and tools to allow for discourses about implicit bias complement the previous chapter’s history and defining approach to implicit bias to provide a complete framework for reading this book.