Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder that is the leading genetic cause of infant mortality. SMA is caused by the loss of survival motor neuron-1 (SMN1). In humans, a nearly identical copy gene is present, called SMN2. SMN2 is retained in all SMA patients and encodes an identical protein compared to SMN1. However, a single silent nucleotide difference in SMN2 exon 7 results in the production of a spliced isoform (called SMNDelta7) that encodes a nonfunctional protein. The presence of SMN2 represents a unique therapeutic target since SMN2 has the capacity to encode a fully functional protein. Here we describe an in vivo delivery system for short bifunctional RNAs that modulate SMN2 splicing. Bifunctional RNAs derive their name from the presence of two domains: an antisense RNA sequence specific to a target RNA and an untethered RNA segment that serves as a binding platform for splicing factors. Plasmid-based and recombinant adeno-associated virus vectors were developed that expressed bifunctional RNAs that stimulated SMN2 exon 7 inclusion and full-length SMN protein in patient fibroblasts. These experiments provide a mechanism to modulate splicing from a variety of genetic contexts and demonstrate directly a novel therapeutic approach for SMA.