The gabapentinoid drugs gabapentin and pregabalin (Neurontin® and Lyrica®) are mainstay treatments for neuropathic pain and for preventing focal seizures. Both drugs have similar effects to each other in animal models and clinically. Studies have shown that a protein first identified as an auxiliary subunit of voltage-gated calcium channels (the alpha2-delta subunit, α2δ-1 or Cava2d1) is the high-affinity binding site for gabapentin and pregabalin, and is required for the efficacy of these drugs. The α2δ-1 protein is required for the ability of gabapentin and pregabalin to reduce neurotransmitter release in neuronal tissue, consistent with a therapeutic mechanism of action via voltage-gated calcium channels. However, recent studies have revealed that α2δ-1 interacts with several proteins in addition to voltage-gated calcium channels, and these additional proteins could be involved in gabapentinoid pharmacology. Furthermore, gabapentin and pregabalin have been shown to modify the action of a subset of NMDA-sensitive glutamate receptors, neurexin-1, and thrombospondin proteins by binding to α2δ-1. Thus, these effects may contribute substantially to gabapentinoid therapeutic mechanism of action. SIGNIFICANCE STATEMENT: It is widely believed that gabapentin and pregabalin act by modestly reducing the membrane localization and activation of voltage-gated calcium channels at synaptic endings in spinal cord and neocortex via binding to the α2δ-1 protein. However, recent findings show that the α2δ-1 protein also interacts with NMDA-sensitive glutamate receptors, neurexin-1α, thrombospondins (adhesion molecules), and other presynaptic proteins. These newly discovered interactions, in addition to actions at calcium channels, may be important mediators of gabapentin and pregabalin therapeutic effects.