Biology education research has now reached a level of maturity where the expectation is that researchers will assess the effectiveness of their innovation on student learning. This may include an examination of affective outcomes, such as student attitudes and beliefs, as well as student understanding of discipline-based content. A variety of tools are available to generate assessment data, each with certain advantages and disadvantages. They include not only quantitative measures, which lend themselves to familiar statistical analyses, but also qualitative techniques that can provide a rich understanding of complex outcomes. This article describes some of the most commonly used assessment techniques, their advantages and disadvantages, and typical ways such information is reported.