Reliable and repeatable measurement is a key component to all engineering disciplines. The same holds true for synthetic biology, which has also been called engineering biology. However, the ability to repeat measurements in different labs has been difficult. The Measurement Committee, through the InterLab study, has been developing a robust measurement procedure for green fluorescent protein (GFP) over the last three years. We chose GFP as the measurement marker for this study since it's one of the most used markers in synthetic biology and, as a result, most laboratories are equipped to measure this protein.