The coarsening behavior of coherent Ni3Si precipitates in six binary Ni–Si alloys with Si concentrations of 10.98, 11.42, 11.74, 12.69, 13.38 and 14.35at.% Si was investigated using transmission electron microscopy (TEM) and magnetic analysis. The equilibrium volume fraction, fe, of Ni3Si in these alloys ranges from ∼0.03 to ∼0.30. The four most concentrated alloys were aged at 650°C for times up to 2760h and investigated using magnetic analysis to supplement an earlier TEM investigation. Unimodal dispersions of Ni3Si precipitates could not be obtained in the 10.98 and 11.42% Si alloys by isothermal aging at 650°C. Therefore, these alloys were first aged at 530°C for 163h and then re-aged at 650°C for times ranging from 120 to 1175h. This seeding and re-aging treatment was successful in producing unimodal dispersions. The alloy containing 11.74at.% Si, investigated previously, was also subjected to the seeding and re-aging treatment to serve as a check on the procedure. The coarsening kinetics were consistent with data from previous investigations for fe>0.10 in that there is virtually no effect of fe. For fe<0.10 there is some evidence that the relationship between coarsening behavior and fe is anomalous because the rate constants for the kinetics of average particle growth and supersaturation depletion, as well as the standard deviations of the particle size distributions, all decrease slightly as fe increases. The values of the diffusion coefficient derived from analysis of the data are in good agreement with those from previous work, but the average value of the Ni3Si/matrix interfacial free energy (derived assuming ideal solution thermodynamics for the matrix phase) is about 10% smaller, ∼8.9mJ/m2. It is suggested that elastic interactions, even in Ni3Si precipitates with their small lattice mismatch (−0.0023), are important in retarding coarsening kinetics in this system. This conjecture is supported by the strong spatial correlations observed in all the alloys, even the one in which fe≈0.03.