RReShar (Regeneration and Resource Sharing) is a functional - structural model aiming at modelling forest dynamics, and particularly the regeneration stage, according to resource availability. It is implemented under the simulation platform named Capsis helping to run and compare different scenarii of forest stand dynamics. In RReShar stand structure is explicitly described, including all the strata of the forest ecosystem, i.e. adult trees, suppressed trees, saplings and seedlings growing in the understorey (regeneration) and herbaceous/shrubby vegetation. This detailed description of stand structure allows to take into account biotic and abiotic processes of interaction (competition / facilitation) between the different components. Growth and mortality functions are based on the interactions with light and water in this model version.