This Chapter highlighted four key areas necessary for the development of SCMs, with the aim of replicating the wealth of information provided by molecular-scale studies. The Surface Site Identity and Reactivity section underscored the significance of understanding populations and spatial distribution of (hydr)oxo functional groups across diverse crystallographic faces of multifaceted particles. This understanding is indispensable for formulating surface complexation reactions that accurately depict coordination environments and geometries, aligning with experimental and/or simulation studies. The section elucidated both numerical and experimental tools applicable to identifying sites on both ideal and less ideal mineral surfaces. Building upon this foundation, The Hydrated Interface section presented essential aspects necessary for understanding mineral surface hydration, counterion adsorption, and links to protonation of surface O(H) groups. Emphasizing the distinct hydration and coordination environments of various crystallographic terminations, it also highlighted the roles of local hydration at intersections of adjacent crystallographic faces. The implications of interfacial hydration on charge development were then presented in The Charged Interface section. A SCM framework was introduced to predict charge development and surface complexation reactions on complex mineral particles. This framework was extended to dynamic capacitance approaches, incorporating the effects of electric fields and interfacial ion solvation effects on the charge-storage capability of the mineral/water interface. Finally, in The Electrochemical Interface section, efforts to independently verify EDL properties using electrochemical methods were presented. Addressing the disparity between properties inferred by SCMs and those measured electrochemically, this section raised concerns about extrapolating knowledge form of macro-scale mineral specimens to nanoparticles. Interconnecting these four aspects-site identity, hydration, surface charge, surface potential-is crucial for the evolving field of SCM research. As the demand for SCMs reflecting molecular-scale observations will intensify in the years to come, a comprehensive understanding of these domains will be pivotal in shaping the future of surface complexation modeling.