The signal recognition particle (SRP) and its membrane-bound receptor (SR) deliver membrane proteins and secretory proteins to the translocation channel in the plasma membrane (or the endoplasmic reticulum). The general outline of the SRP pathway is conserved in all three kingdoms of life. During the past decade, structure determination together with functional studies has brought our understanding of the SRP-mediated protein transport to an almost molecular level. An impressive amount of new information especially on the prokaryotic SRP is integrated into the current picture of the SRP pathway.