The guide explains the roles of standards-based assessment in various contexts involving students who are learning English as a second language (ESL). It is designed to accompany the "ESL Standards for Pre-K-12 Students," a document that sets out the language competencies needed by ESL students to become fully proficient in English, have unrestricted access to grade- appropriate instruction in challenging academic subjects, and ultimately lead rich and productive lives. The first section provides a conceptual model for assessment, including a description of the phases of the assessment process and basic principles for consideration when assessing ESL students. The second section shows the purposes of assessment and the stakeholders' involvement in the process. Section three describes and distinguishes among different approaches to assessment (criterion-referenced, norm-referenced, language proficiency, academic achievement, direct performance, indirect performance), and the last section discusses some general uses for assessment data. Contains 9 references. (MSE)