Abstract. Young Open Clusters have always been a platform for the star formation studies. It was assumed that all members in the cluster are coeval, on the other hand, recent studies show the presence of an age range among the members of young open clusters. Presence of pre-main sequence (PMS) stars are identified by combining optical and near-IR data for 13 young clusters. Age-wise and mass-wise distribution of PMS stars are analysed to study how star formation proceeded in the clusters. In all the clusters we studied, we find an age range among the PMS stars and the duration of star formation is found to be similar to the cluster age.

Key words: stars: formation -- stars: pre-main sequence -- (Galaxy:) open clusters and associations: general