Computational thinking is a fundamental skill that extends beyond computer science. Conceptually it involves logic, algorithms, patterns, abstraction, and evaluation. The approach for developing a computational mind-set may involve experimenting, creating, debugging, and collaborating. Due to certain implicit biases and societal and cultural factors, girls may not be exposed to these computational thinking concepts and approaches. This has resulted in a decrease in the number of women in computer science since the 1980s. This chapter summarizes some of the challenges faced when teaching introductory computer science to high school girls and the approaches taken to overcome those challenges.