A DWBA formalism is presented for the quasi-free breakup of 3He into elastic, inelastic and particle-transfer channels. The model assumes that only a subset of the projectile interacts strongly with the target while the remaining fragment acts as a spectator. The full DWBA is reduced to a rather transparent quasi-free reaction mechanism. Distortion of the spectator wave function due to the Coulomb field of the target is included. Calculations of angular correlations and projected energy spectra resulting from processes involving the binary breakup of 3He on 28Si at E(3He) = 52 MeV are, apart from a normalization factor, in good agreement with the data.