Spatial spreading is performed in a multi-antenna system to randomize an “effective” channel observed by a receiving entity for each transmitted data symbol block. For a MIMO system, at a transmitting entity, data is processed (e.g., encoded, interleaved, and modulated) to obtain ND data symbol blocks to be transmitted in NM transmission spans, where ND≧1 and NM>1. The ND blocks are partitioned into NM data symbol subblocks, one subblock for each transmission span. A steering matrix is selected (e.g., in a deterministic or pseudo-random manner from among a set of L steering matrices, where L>1) for each subblock. Each data symbol subblock is spatially processed with the steering matrix selected for that subblock to obtain transmit symbols, which are further processed and transmitted via NT transmit antennas in one transmission span. The ND data symbol blocks are thus spatially processed with NM steering matrices and observe an ensemble of channels.