INTRODUCTION The ability to rear Hawaiian bobtail squid ( Euprymna scolopes ) embryos under controlled environmental conditions is a basic and necessary tool for developmental studies. It negates the need to know when fertilization occurred, allows correlation of the phase of development with the time of development (thereby facilitating collection of embryos at specific stages), and allows comparisons between cephalopod species. Embryonic development in E. scolopes is robust over a range of temperatures, is relatively rapid (~21 d), and proceeds normally under laboratory conditions at ambient temperature (27°C-29°C). Here we present methods for maintaining E. scolopes embryos in culture from cleavage through hatching, as well as observing and recording live or freshly fixed embryos under a dissecting microscope.