This volume reports on the oral and poster presentations during the II Algal Photobiology Workshop held in Málaga from October 10th to 14th, 1994. The aim of this meeting was to conduct an interdisciplinary discussion on algal photobiology from molecular to ecophysiological scale. The role of light (ultraviolet and visible) on algal metabolism and growth was analyzed in both micro and macroalgae. The light was treated as energy source in photosynthesis and and as informational signal from natural enviroment modulating algal morphogenesis. The main objective is to discuss the processes that occur in algae looking for functional and controlling aspects common for both micro and macroalgae, as for example carbon concentration mechanisms, nitrogen assimilation, photoacclimation to high and low irradiance, photoinhibition and photoprotection processes, photomorphogenesis and photocontrol of growth.