Females are often overlooked as potential perpetrators of sexual offending; perhaps because they are few in number compared to their male counterparts. Although it is difficult to know the true figure of females who sexually offend, researchers estimate that women commit between 4 to 5 per cent of all sexual crimes (e.g., Cortoni & Hanson, 2005; Cortoni, Hanson, & Coache, 2009; Cortoni, Babchishin, & Rat, 2017). However, it is becoming increasingly obvious that despite the seemingly small numbers (relative to males), an effective theory of female-perpetrated sexual offending is crucial for the development of treatment strategies (Beckett, 2005; Ford, 2006). This chapter provides a brief summary of the characteristics of females who sexually offend, followed by a review of current theory available to explain sexual offending perpetrated by females. In addition, several of the key characteristics and potential treatment needs of women who sexually offend shall be discussed alongside recommendations for treatment.