This study provides evidence that overgeneralization of causatives by L1 Spanish/L2 English and L1 English/L2 Spanish learners is driven by selective L1 transfer at different levels of proficiency. Not all aspects of the grammar are transferred at once. Properties of the causative construction are transferred first; verb-specific properties, later. Pre-advanced learners overgeneralize L1 properties of the causative construction: they overgeneralize causatives more with verbs of change of state/location. Advanced learners focus on properties of specific verb classes: they restrict the overgeneralization of causatives to verbs that are allowed in lexical causatives in their L1. Our analysis provides a unified account of the overgeneralization of causatives. Issues related to the L2 initial state and to recoverability from overgeneralization and undergeneralization are discussed.