Analyzing long-term demographic data from the Schools and Staffing Survey, Ingersoll and Merrill found a number of intriguing trends in the teaching force that they say "appear to have been little noticed by researchers, policymakers, and the public." The number of teachers, they write, is growing at a rate that far outpaces increases in student enrollments. Both the proportion of teachers who are nearing retirement age and the proportion of teachers who have just 1-2 years of experience are rising. The proportion of teachers who are female, already high, is growing. Teacher turnover is also increasing, and turnover rates are higher in high-poverty, high-minority, urban, and rural schools. The academic ability of teachers remains lower than that of other professions. The authors discuss some of the possible reasons for and implications of these trends. (Contains 2 figures and 1 endnote.)