An experimental method for directly determining the degree of interconnectivity of melt in a partially molten system is discussed using an olivine-basalt system as an example. Samarium 151 is allowed time to diffuse through mixtures of olivine and basalt powder which have texturally equilibrated at 1350¿C and 13 to 15 kbars. The final distribution of samarium is determined through examination of developed radiographs of the samples. A uniform distribution of samarium throughout an entire sample implies the melt is present as an interconnected network because diffusion of samarium along melt-free grain boundaries is shown not to occur in the time frame of these experiments. Quantitative determination of the degree of interconnectivity is done by establishing a one to one correspondence between a sample and its radiograph. Results suggest an interconnected melt network is established at melt fractions at least as low as 1 wt % and all melt is completely interconnected at melt fractions at least as low as 2 wt % for the system examined. ¿ American Geophysical Union 1988