Aqueous interfaces are ubiquitous across atmospheric, biological, and technological processes. Interfacial water is thought to play an active role in many of these processes. For instance, hydrophobic coatings are used for anti-biofouling and the interaction between water molecules and the hydrophilic coatings is believed to inhibit protein adhesion. However, the precise role of water is not well understood. Interfacial water is also notoriously difficult to study experimentally since the number of water molecules at the interface is miniscule compared to the bulk and the ultrafast fluctuations of the hydrogen-bonding network require sub-picosecond time resolution. Sum-frequency generation (SFG) is a second-order nonlinear spectroscopy that is sensitive to only the vibrations of interfacial water due to the requirement of broken inversion symmetry within the dipole approximation. Using hydrophobic, hydrophilic and mixed hydrophobic/hydrophilic self-assembled monolayers, we examined the structure of the interfacial water with heterodyne-detected SFG (HD-SFG) to obtain the purely absorptive vibrational line shape. In order to probe the dynamics of the hydrogen-bonded interfacial water, we performed time resolved SFG experiments. The vibrational relaxation time was measured using IR pump- SFG probe experiments, and the spectral diffusion time was measured with interferometric 2D SFG.