Enzymes in RNA Science and Biotechnology, Volume 691 in the Methods in Enzymology series, highlights new advances in the field, including chapters on Reverse transcriptase Part I (discovery, preparation, general utilization, MarathonRT for routine RT-PCR and for cDNA synthesis on challenging RNA templates Structured RNAs, repeat RNAs and more, Engineering TNA Polymerases Through Iterative Cycles of Directed Evolution, Reverse transcriptase Part II (RNA structure mapping and determination), RNA G-quadruplex (rG4) structure detection using RTS and SHALiPE assays, tRNA Structure-seq in vivo and in droplets, Capture the in vivo intact RNA structurome by CAP-STRUCTURE-seq, and more.