Abstract　 　 
My research focus is the study of stellar clusters. It covers both theoretical aspects and applying the theoretical models to observed stellar clusters. I am member of the GALEV evolutionary synthesis models team. The GALEV models provide integrated magnitudes and spectra (now available for a spectral resolution down to 0.02 Angstroem) of stellar clusters and galaxies. It includes the effect of gaseous emission, cluster dissolution and soon binary star evolution as well. The modelling of dissolving stellar clusters is directly related to N-body simulations, for which I studied the reliability and reproducibility of N-body simulations using different N-body simulation codes and different hardware (i.e. different calculation accuracies). The main advantages of stellar clusters are: 1) their rather simple stellar populations (though recently the existence of multiple stellar populations was discovered), which enables more detailed and reliable modelling, 2) high surface brightness and contrast to the field star population allows the study of individual stellar clusters to significantly larger distances than resolved stellar populations and 3) the relation between enhanced cluster formation and field star formation simplifies the determination of SFHs of the host galaxy.