Systematic tax reform, that ever-elusive but ever-desirable elf, has made some appearances recently before quickly ducking out of sight. Although many tax enactments involve changing the boundaries of the tax system - say, tax rates or deductions or limits - history warns us that seldom has systematic reform succeeded. Systematic reform recognizes important societal trade-offs, and trade-offs mean that something must be given up to achieve something better. With this string of failures in mind, I thought it might be useful to set out some broad guidelines for engaging in a process that enhances the probability of success. For the record, most of these guidelines for reforming the tax system apply equally well to budgetary and expenditure reform.