Among the principal uses of the detectionFourier transform infrared spectroscopydetection (FT-IR) methods described in the previous chapter, especially the physical methods, is the determination of macromolecular architectureArchitecture, second only to the determination of molar mass averages and distributions. In this chapter, we detail many of these architectural metrics, including long- andBranchingshort-chain branching (SCB) short-chainShort-chain branching (SCB) branchingBranching, dilute solution conformationDilute solution conformation, fractalDimensionfractal dimension, persistence lengthPersistence length, characteristic ratioCharacteristic ratio, and several dimensionless parameters. How to evaluate each of these is explained along with requirements for accurate quantitation.