Somatic embryogenesis is increasingly becoming one of the most important processes for the successful regeneration and micropropagation of plant species. Primary and secondary somatic embryogenesis (most suitable explants for synthetic seed technology), when coupled to cryopreservation, allow for an effective method for long-term germplasm conservation. With successful somatic embryogenesis having been reported in numerous genera within the Angiosperms and Gymnosperms, thin cell layer (TCL) technology, allowing for the successful, controlled production of somatic embryos in otherwise recalcitrant species, has further enhanced the importance of somatic embryogenesis in plant (micro)propagation, preservation and genetic transformation. This review examines the success of somatic embryogenesis by TCL culture in a number of economically important species, and further examines its application in practical, genetic transformation procedures.