This report provides a summary of the fourth workshop on quantified economy-wide emission reduction targets by developed country Parties. The workshop was held in Bangkok, Thailand, on 2 September 2012, during the informal additional session of the Ad Hoc Working Group on Long-term Cooperative Action under the Convention. As part of the process of clarification of the targets, the workshop addressed the approaches to measure the progress towards achievement of the targets by developed country Parties, the ambition of pledges and related assumptions and conditions, and possible ways forward