Women and girls in the United States continue to be underrepresented in STEM, particularly in engineering and technology fields. This gap has been attracting recent attention from those motivated to ensure that girls and women have access to a full range of personally satisfying careers as well as from those concerned with developing a rich talent pool to meet national workforce needs. This chapter is focused on interventions that have been designed to address this STEM gender gap. We begin by documenting the STEM gender gap and then review change mechanisms emerging from theories of gender development that may be harnessed in intervention efforts. In addition, we provide a taxonomy of intervention goals which we then use to organize an illustrative review of sample interventions. After commenting on some of the findings and limitations of past work, we offer suggestions for enhancing the systematic evaluation of intervention programs that include careful selection of comparison groups, a broad array of STEM outcome measures, assessment of potentially unintended consequences, and meta-analyses.