Some American cities demand that developers pay "linkage feeg' (some- times cared exactions) over-and-above required property- taxes. Presumably, these are meant to cover short-term costs and "social impacts" that exceed the development's expected tax pay- ments. The level of linkage payments in each city is determined either through case-by-case negotiations (as in Boston) or by the application of a formula that assumes an average charge per square foot (as in San Francisco). My aim in this column is to review the strengths and weaknesses of these two approaches, then describe still another approach that I think will produce superior negotiated development agreements.