The critical velocity of engulfing V c of acetal, nylon-6,6, and nylon-12 particles when encountered by the solidification front of salol is reported as a function of particle size. Using the dimensional analysis derived previously, the free energy of adhesion ΔF adh for the attachment of these particles to the salol solid/melt interface is determined. These values of ΔF adh, together with the known surface tension values γ PV of the particles, are used to determine the salol solid/melt interfacial tension γ SL to be γ SL = 0.0053 ± 0.0025 erg/cm 2. Similarly, the free energies of adhesion ΔF adh for PMMA particles to the solid/melt interfaces of naphthalene, biphenyl, and salol are determined. As all the γ SL values for these systems are known—in the case of naphthalene and biphenyl from the temperature dependence of contact angles— γ PV for the PMMA particles is determined. Using the equation of state for interfaces, the contact angle for the system PMMA/water is predicted. This value is in excellent agreement with the contact angle of water on a film of PMMA obtained by solvent casting. It is concluded that measurement of the critical velocity of engulfing represents a unique method for contact angle determinations on small particles.