U.S. state and local policy frameworks treat teacher evaluation as balancing two aims: accountability and skill development. I develop a model of teacher effectiveness and detail the conditions that determine joint-aim appraisal systems’ contribution to teacher productivity. I then simulate the long-term effects of a set of teacher evaluation policies. Policies that treat evaluation for accountability and evaluation for growth as substitutes outperform those that treat them as complements. I conclude that an optimal teacher evaluation policy would impose accountability on teachers performing below a defined level and above which teachers would be subject to no accountability pressure but would receive intensive instructional supports.

美国州和地方政策框架将教师评估视为平衡两个目标：问责制和技能发展。我开发了一个教师效率模型，并详细说明了决定联合目标评估系统对教师生产力贡献的条件。然后，我模拟了一组教师评估政策的长期影响。将问责评估和增长评估视为替代的政策优于将它们视为补充的政策。我的结论是，最佳的教师评估政策将对低于规定水平和高于规定水平的教师施加问责制，教师将不受问责压力的影响，但会得到强化的教学支持。