This chapter explores the issue of assessment, from the definition and purposes for assessment to the construction of mathematics tests and the use of alternative strategies for measuring progress. Teachers conduct a pre-assessment—some sort of assessment activity conducted before designing a unit—to determine the needs of their students. Many teachers make use of technology to accomplish the purpose of pre-assessment. Educators generally differentiate between two other types of assessment—formative and summative. The chapter describes some of the uses for data collected through the assessment process. Every teacher should use a combination of formative and summative assessments to monitor and validate student learning. Assessment should provide clear information about what students are thinking for the teacher to fine-tune the lesson or unit accordingly. The chapter examines some assessment strategies, beginning with the more traditional written tests and explores such alternatives as the use of journals and portfolios.