The accurate assessment of agricultural greenhouse gas emissions (GHGs) for accounting and mitigation options is still a key concern. An extensive body of data is available, but limitations of the different measuring approaches have often been ignored. Despite some constraints, chamber-based approaches have dominated annual assessments of GHGs to provide information on spatial and temporal variations. The Eddy Covariance (EC) technique has become the approach of choice and the basis of international monitoring networks. It has restricted applicability due to footprint constraints, poor replicability, complexity and high cost, meriting new approaches for replacement or complement to. For enteric CH4 emissions from livestock systems, respiratory chamber, tracer or GreenfeedTM techniques, having limitations for confined animals and requiring significant technical expertise, can be used. An overview of other livestock-associated approaches is given in this chapter. This argues for more investment in alternative methods for routine on-farm measurements and the identification of mitigation options.