Transcription often initiates divergently but it only proceeds in the sense direction. These authors, working in mouse embryonic stem cells, have elucidated a mechanism for regulating divergent transcription. They find that antisense transcripts are cleaved and polyadenylated shortly after initiation. This is due to asymmetric positioning of sequence elements: sense transcripts are depleted for polyadenylation sites and are enriched for binding sites for the U1 SNP ribonucleoprotein. Depletion of the U1 SNP led to promoter-proximal cleavage in the sense direction, indicating a regulatory role for this ribonucleoprotein.