We define a saltatory phonological alternation as one in which sound A is converted to C, leaping over phonetically intermediate B. For example, in Campidanian Sardinian, intervocalic /p/ is realised as [β] – leaping over [b], which does not alternate. Based on experimental evidence, we argue that saltation is marked, i.e. a UG bias causes language learners to disprefer it. However, despite its marked status, saltation does occur. We survey its diachronic origins, and suggest that it is never introduced as a sound change, but arises only from a variety of historical accidents. For the formal analysis of saltation, we propose a new approach, based on Zuraw's (2007, 2013) *Map constraints and Steriade's (2001, 2009) P-map. This approach is more restrictive than previous proposals, and accounts for psycholinguistic evidence indicating an anti-saltation learning bias: saltation is disfavoured during learning because it is by definition not a P-map-compliant pattern.