Magnetic activity gives rise to a number of variable phenomena in premain sequence stars, main sequence stars and binary systems for instance. Notably, flares and hot and dense outer atmospheres are most commonly observed. We need to investigate theoretically the possible spectral signatures of chromospheres so as to interpret the remarkable variety of observations, and discriminate the chromospheric counterpart to other possible contributions, such as cool coronal loops. Along these lines, here we report on our current progress in modelling main sequence stellar chromospheres.