Inter-grain electron-coupling effects are investigated at 4.2 K in dual-gated, point-contact, single-electron transistors fabricated in nanocrystalline silicon. The nanocrystalline silicon film is similar to 40 nm thick, with grains similar to 10-30 nm in size. The point-contact transistor channel is similar to 30 nm x 30 nm x 40 nm in size, with two side-gates. Only a few grains exist within the channel and different grains contribute in varying degrees to the device conduction. By modifying the inter-grain coupling using selective oxidation of the grain boundaries, both electrostatic and wavefunction-coupling effects can be observed in the Coulomb oscillations vs. the two gate voltages. (C) 2005 Elsevier B.V. All rights reserved.