In biobank networks, accrual, aggregation, and retrieval of samples and data are impeded if minimal standards are not agreed in advance by the network members. The critical requirement is that outputs be standardized between biobanks. To start to address this problem of minimal standards, we undertook a pilot study and now report a follow-up study with 79 centers to identify sources of variability in a common measurement-the estimation of DNA concentration. Our main findings include confirmation of the results of the pilot study on overall variability between centers; fluorescence spectroscopy yields lower estimates of concentration and has less accuracy than absorption spectroscopy; and the 2 technologies differ in their sensitivity to mixing of the samples before measurement. We found that more recent servicing of liquid handling devices contributes to accuracy (at least when deploying absorption spectroscopy). We conclude that, while further study is required, there is a need to promote the development of complete Standard Operating Procedures in academic and commercial laboratories with the implementation of management systems that ensure full adherence to those procedures. There also needs to be a consensus on how much variability in measurements is acceptable for each downstream platform for technologies, including genotyping, sequencing, and epigenetics.