The early development of the hard coral Acropora millepora has been described at both the morphological and molecular levels, and comparative studies are under way for other Scleractinia. Complementary data on Octocoral embryogenesis are, however, essential for a broader understanding of the different developmental strategies in Cnidaria and their evolution. Although the morphology of soft coral embryogenesis has been previously described, data are scarce and molecular data complementing the morphology are missing. This thesis involves the investigation of reproduction and early development in soft corals, using Lobophytum pauciflorum as model. As in the majority of soft corals, L. pauciflorum colonies are either female or male. The time of reproduction approximately coincides with the annual synchronised mass spawning of hard corals on the Great Barrier Reef (GBR), although in favourable years studied, it occurred a lunar month earlier. The process of gametogenesis is longer in the gonochoric soft coral than in the hermaphrodite hard coral A. millepora or the gonochoric hard coral Fungia concinna. However oogenesis is completed within a year, which is shorter than has been reported for a conspecific population in Taiwan. In addition, bidirectional sex change was observed in F. concinna, suggesting that this trait could also be a predominant reproductive feature in fungiid corals. After studying the gametogenic cycle of L. pauciflorum on the GBR and identifying the time point of spawning as 4 − 5 nights after the austral spring full moon, investigation of early development was possible. Following mixing of eggs and sperm, the first obvious signs of successful fertilisation occurred at the 16 − 32 cell stages. Through a series of cell divisions leading to irregular shapes, embryos developed into a swimming planula within 48 hours of fertilisation. Planulae then stayed in the water column for up to a week before settling and developing into a primary polyp with 8 tentacular buds in the 24 hours after settlement. ...