The Environmental Impact Assessment in the Mekong Region manual is the first time that anyone has sought to bring together in one volume an analysis of the EIA systems of each of the six Mekong countries, including the common themes and approaches. This was also the first project undertaken by the MLN, in collaboration with ERI. As a result, there was a lot of learning throughout the process of collaboration and collation from all involved. Whilst all of the members of the MLN are experienced lawyers, we found that there was a gap between law and practice. There was also the need to be able to communicate in a transboundary way, while acknowledging that different countries used different processes and with some different approaches to EIA.