Symmetry breaking in CSPs has attracted consid erable attention in recent years. Various general schemes have been proposed to eliminate sym metries during search. In general, these schemes may take exponential space or time to eliminate all symmetries. This paper studies classes of CSPs for which symmetry breaking is tractable. It identifies several CSP classes which feature var ious forms of value interchangeability and shows that symmetry breaking can be performed in con stant time and space during search using dedicated search procedures. Experimental results also show the benefits of symmetry breaking on these CSPs, which encompass many practical applications.