This NCER Practice Guide is the second in a series of IES guides in education. Developed by a panel of experts, this guide brings together the best available evidence and expertise to provide educators with specific and coherent evidence-based recommendations on how to encourage girls in the fields of math and science. The objective is to provide teachers with specific recommendations that can be carried out in the classroom without requiring systemic change. Other school personnel having direct contact with students, such as coaches, counselors, and principals may also find the guide useful. The guide offers five recommendations and indicates the quality of the evidence that supports the recommendations. Together, the recommendations make a coherent statement: To encourage girls in math and science, educators need to strengthen girls' beliefs about their abilities in math and science, spark and maintain greater interest in these subject areas, and build associated skills.