This study was focused on coalescence in highly concentrated emulsions stabilized by a whey protein isolate or by sodium dodecyl sulfate. For both stabilizers, coalescence of the emulsion at rest occurred below a critical concentration of the stabilizer. This concentration was related to full coverage of the droplet interface. Coalescence proceeded until the internal area of the emulsion was sufficiently reduced to obtain full coverage by the stabilizer. Above the critical stabilizer concentration, this mechanism of-coalescence was almost completely inhibited. Coalescence could also be induced by subjecting the emulsion to external forces that made the emulsion flow. Coalescence induced by flow occurred much more readily for the protein-stabilized emulsion than for the surfactant-stabilized emulsion and also occurred above the critical stabilizer concentration. This demonstrated that coalescence induced by flow and coalescence at rest proceeded through different mechanisms.