In recent years, plant-based milk products, commonly called as non-dairy milk alternatives have gained high popularity due to concerns associated with bovine milk like lactose intolerance, allergies, hypercholesterolemia, and pesticide and antibiotic residues. Important strategies for manufacture of non-dairy milk alternatives involve disintegration of plant materials in aqueous medium; its homogenization and addition of some additives to attain a consistency and appearance similar to that of bovine milk. Different range of ingredients are added to non-dairy milk alternatives such as oils, emulsifiers, thickeners, antioxidants, minerals etc. The main problem associated with non-dairy milk alternatives is generally linked with its stability. Stability is a crucial factor that governs the sensory properties and overall acceptance of non-dairy milk alternatives. Differences in processing parameters and molecular interaction mechanisms affect the stability of emulsions as well as the stability of non-dairy milk manufactured thereof. Various treatments like thermal treatment, non-thermal processing (ultra high pressure homogenization, pulsed electric field, ultrasonication), addition of emulsifiers are effective in achieving the stability of non-dairy milks. The present chapter aims to summarize the various factors contributing to the physical stability of non-dairy milk alternatives like appearance, consistency, emulsion stability, and the approaches required to maintain it.