The influence of the dispersed phase volume fraction (0.01 less than or equal to phi less than or equal to 0.4) and emulsification parameters (8 less than or equal to P less than or equal to 76 MPa and 35 less than or equal to T less than or equal to 100 degrees C) on the relative electrical conductivity(sigma(s)/sigma(2s)) of dairy model emulsions, reconstituted milk and creams, and commercial chocolate milks was studied. This study was based both on the use of statistically analyzed experimental designs and classical conductivity models of dispersed systems (Rayleigh-Wiener, Bruggeman, and Bottcher-Landauer). Furthermore, a simple approximation, based on Eveson’s work on the relative viscosity of dispersed systems and derived from the Rayleigh-Wiener equation, was also proposed. This equation describes the electrical conductivity of dispersed systems composed of n classes of dispersed droplets, [GRAPHICS] with sigma(1s)(r) = sigma(1s)/sigma(2s), and where sigma(s), sigma(1s), and sigma(2s) are, respectively, the conductivities of the whole dispersion, the dispersed phase, and the continuous medium. This equation, which is applicable to all systems composed of n different size classes of dispersed particles, represents the link between the Rayleigh-Wiener equation, only valid for monodispersed systems, and that of Bruggeman, valid for infinitely polydispersed systems. The use of the experimental design indicated that only the dispersed phase volume fraction, which explained 94% of the total variance, had a statistically significant effect on the model emulsion sigma(s)/ sigma(2s) ratio. Emulsification factors were found to have no measurable effect on the conductivity. A comparison with theoretical equations revealed that if all experimental data (with the exception of chocolate milks) fell on lines corresponding to the above four models, for phi less than or equal to 0.15, only the model of Bruggeman and the above equation for n = 3 or 4 allowed a satisfactory description of the conductive behavior of this type of emulsion for the whole domain of phi studied. Moreover, the number n = 3 or 4 of different fraction sizes is a theoretical number as it is clear that the fat globule size distribution of a dairy emulsion is both continuous and polydispersed.