At the turn of the millennium, public pensions were more generous than ever and yet seemed to be fully funded. But the two decades that followed have decimated the finances of many public-pension funds, resulting in steeply rising taxpayer costs and serious risk to public workers' salaries, jobs, and benefits. At this point, while the economy is strong, there is time and room to address these problems — by improving the accuracy of pension-cost estimates, increasing accountability for making full payments every year, and modernizing benefits to help all workers save. But waiting until the next recession could be a disastrous mistake.