Metallic layers can be selectively deposited on one surface of a substrate relative to a second surface of the substrate. In some embodiments, the metallic layers are selectively deposited on a first metallic surface relative to a second surface comprising silicon. In some embodiments the reaction chamber in which the selective deposition occurs may optionally be passivated prior to carrying out the selective deposition process. In some embodiments selectivity of above about 50% or even about 90% is achieved.