The power of an effective teacher and why we should assess it -- How can we assess teacher quality? -- Assessing teacher quality with student work: the Oregon teacher work sample methodology -- Assessing teacher quality in a standards-based environment: the Thompson, Colorado, school district -- Assessing teacher quality through goal-setting: the Alexandria, Virginia, school district -- Assessing teacher quality based on student gains: value-added assessment system in Tennessee -- Final thoughts on assessing teacher quality: guidelines for policy and practic.