The present disclosure provides tricyclic nucleosides and oligomeric compounds prepared therefrom. The tricyclic nucleosides each have a tricyclic ribosyl sugar moiety wherein a bridge between the 2' and 4' ribosyl ring carbon atoms further comprises a fused carbocyclic or heterocyclic ring. The tricyclic nucleosides are expected to be useful for enhancing properties of oligomeric compounds including for example binding affinity and nuclease resistance.
