I'm an optimist and have even been called a relentless optimist. Still, I get depressed when I see the frequency with which ideas for education policy are put forward despite a lack of evidence for their value. Paying teachers based on their students' achievement is one of those ideas. It's a headline issue in the United States. In Canada, there is often much fallout from issues prominent in the United States, so now there also are calls in Canada for some form of pay for performance for teachers, such as that made by one of the unsuccessful candidates for leadership of the governing Liberal Party in British Columbia. My concerns about paying teachers based on student results come from my reading of the evidence in education and beyond. A paper I wrote recently for the Elementary Teachers Federation of Ontario (available at www.etfo.ca/issuesineducation/meritpay/pages/default.aspx) laid out eight reasons why these plans are likely to be bad education policy. 1. Few people in any occupation are paid based on measured outcomes. According to Scott Adams and John Heywood (2009), only 15% to 30% of all workers get any kind of performance pay, most of which is not based on outcomes, and only 6% are in ongoing performance pay systems. Most of this is in sales-related occupations. In the corporate world, there is no relationship between the pay of corporate CEOs and measured performance. If pay based on results makes so much sense, why is it so unusual, even in the private sector? 2. No other profession is paid based on a measured outcome. Professionals are paid primarily based on salaries or on volume of work. Where there is pay for performance for professionals, the performance measures are rarely related to measures of client outcomes. 3. Most teachers oppose such schemes. Surveys of teachers consistently show strong (70+%) opposition to pay schemes based on student achievement. Since improvement in education depends critically on teachers' commitment, anything that reduces commitment is likely to be unhelpful to better school outcomes. 4. Pay based on student achievement is very likely to lead to displacement of other important education purposes and goals. When people have a financial incentive to achieve a score, that incentive may displace other, more desirable efforts. Since not all the important goals of education will be measured, those that are linked to pay are likely to get more attention at the expense of other goals. Research in psychology shows that extrinsic rewards can act to displace intrinsic motivation. Pay schemes based on student achievement measures could reduce some teachers' desire to do the job well simply because that is their professional responsibility and wish. If merit pay is individual and competitive, teachers will have fewer incentives to cooperate and share with colleagues. 5. There is no consensus on what the measures of student achievement should be. Academic achievement is not the only important outcome of schooling; we also value students' ongoing ability to learn, interest in learning, abilities to work with others, and citizenship skills. Most of these, however, would not be used in a merit-pay scheme. Even restricting the focus to academic achievement, there is the issue of how that should be measured. Does one measure all subjects or only some? Does one measure the absolute level of attainment, which is strongly influenced by prior attainment, or the incremental gain in learning? In that case, it can be very hard to show gains if students are already performing well. …