A mathematical model was conceived and constructed to estimate the dynamic behavior of Dunaliella salina beta-Carotene cultivation systems under different operating and environmental conditions. A parametric sensitivity analysis identified the most influential model parameters. which were then adjusted to a set of actual laboratory data obtained under a nide range of controlled conditions. The adjusted model was shown to be qualitatively correct, leading to simulated system behavior that is in agreement with what one would expect from experience, literature and cell physiology., It was used to analyze and compare bioreactor design, operating strategies, scenarios and conditions in order to optimize Dunaliella salina beta-Carotene cultivation systems under different environmental conditions. Namely, for an open air production plant it was found out that a two stage process (growth in a first pond, followed by dilution into a second pond) is better than a single stage, because it leads to higher beta-Carotene contents and productivity.