Although the Doha declaration, launching the current multilateral trade negotiations, puts special and differential treatment (SDT) at its core, negotiations have made no progress. This Bulletin explains why SDT is central to the creation of development-friendly trade rules and has become more necessary since the World Trade Organization (WTO) was created. This is because dispute settlement is now binding. Differences could be accommodated under the General Agreement on Tariffs and Trade (GATT) through ex post fudging. The problems experienced with the Agreement on Trade-Related Intellectual Property Rights (TRIPS) demonstrates what can go wrong and why ex ante agreement is now required. There are many ways in which differentiation can be incorporated into the Doha Round. The key requirement is that it should provide actionable modulations that address the development issue involved. This has strong implications for research, which must be issue and country-specific. It also implies that, while there is a place for WTO- and Agreement-wide statements of principle and for modulations within each country's national schedules, to be effective some SDT will need to be limited to sub-groups of developing countries.