Concentrated emulsions (dispersed phase fractions greater than 1 vol %) have applications in a wide variety of industries. In the energy industry, these emulsions are encountered in every stage of crude oil processing. Characterizing such concentrated emulsions in the presence of surfactants and/or solid particles and in flowing conditions will help develop strategies for managing these complex systems. In this work, an experimental flow loop equipped with an inflow microscope was used to quantify emulsion drop size distributions as a function of the water concentration, flow rate, temperature, and stabilizing agent type. The solid-stabilized emulsions indicated that only the water concentration had an overall impact on the drop size distributions. This work showed that the drop size distribution is a function of the temperature, water concentration, and flow rate for surfactant-stabilized emulsions. The direct, unique experimental insight gained about concentrated emulsions in this work provides a fundamental understanding on their formation and stabilization mechanisms.