This chapter sets out the challenges around the harmonisation of methods for the analysis of genetically modified (GM) food and feed and GM organisms (GMO). A short description of a network approach is provided which has been instrumental in driving forward such DNA analysis. It explains how the European Network of GMO Laboratories (ENGL) is supporting knowledge exchange and the harmonisation of analytical methods required for the implementation of the European Union (EU) regulatory framework on GMOs in food and feed. Major examples of ENGL output are listed and put in context to other activities facilitating reliable GMO analysis.