Long before psychology, bias has existed in science. From the beginning, concerns have been raised about the reliability, validity, and accuracy of social science research (Meehl, 1954). In this chapter, we define and discuss the origins of bias and how it can erode the scientific method. We focus specifically on bias in psychological research, theory, assessment, and treatment. We discuss the range of common misconceptions and misinformation that permeates the female offender literature. Finally, we conclude with ten myths about female offenders and offer guidelines for identifying bias and how to avoid it.