During the lysogenic life cycle, the genome of temperate phages is integrated into the bacterial chromosome. Following induction of the lytic life cycle, phage DNA is packaged into virions and phage progeny is released by host cell lysis. Thus, phages are considered to be parasites that exploit bacterial cells for survival and proliferation; however, the phage–host interaction is also mutualistic. For example, phages drive bacterial evolution by delivering bacterial DNA fragments to neighbouring bacteria by generalized transduction. This study reports that DNA transfer not only benefits the recipient host but also the transducing phage. The authors showed that transduction of antibiotic resistance genes and lysogeny contribute to the survival of transducing phages and their hosts, as recipient cells become resistant to both antibiotics and phage attack. They propose that generalized transduction is an evolved mutualistic trait whereby temperate phages cooperate with their hosts to survive.