Assesing Mathematical Understanding and Skills Effectively   The main goal of Balanced Assesment is to produce assessment that can be used in classrooms throught the nation - assessments that reflect the values of the mathematics reform movement as articulated in the National Concil of Teachers of Mathematics Curriculum and Evaluation Standards. This assessments are designed to provide students, teachers, schools and parents with useful information about how students and programs are doing with respect to those standards. What are the Purposes of Assessment? As a society and as educators, we assess both performance and competence in education in a variety of ways and for a variety of purposes. Broadly speaking the purposes are Serving instruction, Accountability, Selection and Licensure. Assessing student performance in order to inform instruction is something that all teachers do. It is often the case that an external agency of some sort gets involved in assessment, nominally to serve instruction. The time lapse between the administration of the tests and the reporting of "scores" to teachers who might be able to use the information is such that there is little reason to assume that any such testing by an external agency has much to contribute to assessment for instruction. Assessing for the purpose of saying how well a student, or a class, or a school, or an instructional program is doing is the primary purpose of assessment for accountability. Traditionally such information has been presented in one of two quite different forms, norm-referenced and criterion-referenced. Norm-referenced accountability statements involve comparing students' performance (or classes or schools) to one another and then presenting the results of those comparisons in rank order. It should be noted that this can only be done if the performance of the students can be encoded in a unidimensional measure. Criterion-referenced accountability statements involve comparing students' performance (or classes or schools) to some predetermined set of performance criteria without regard to how they compare to one another. It should be noted that this can only be done if one has a clearly defined set of performance criteria that reflect one's theory of competence in the domain being assessed. Assessing for selection is normally done for the purpose of helping to ascertain whether a student will have access to limited resources. Such assessment is often employed in order to inform decisions about access to select universities, programs for gifted music students, special education programs, etc. Assessing for the purposes of licensure is normally done in order to ascertain whether the people being assessed have exceeded some threshold of minimal competence and are thus permitted to practice in an unsupervised fashion the skill that they have demonstrated. Such skills include driving automobiles, swimming in the deep part of the pool, larbering, butchering, working as an electrician or a plumber, etc. Although it has never clearly articulated its stance with respect to these purposes, the Balanced assessment project has focused it's attention primarily on assessment to serve instruction and assessment for accountability, largely through the mechanism of assessing the performance of students on collections of tasks that the BA sites devised or adapted.