GPS based techniques allow a highly accurate attitude determination when using carrier phase measurements. However, these techniques require the determination of the integer carrier phase ambiguities. This is a problem that is usually addressed in a context of dual frequency receivers. Due to the high cost of these receivers, strong motivation exists to explore these techniques with cheaper L1 single frequency receivers. In this paper, a high accuracy attitude determination technique is proposed, based on multiple baselines, using low cost single frequency L1 GPS receivers. Test results with real data are presented.