I developed an analytic model of halo mass accretion histories using the extended Press-Schechter formalism. In Correa et al. (2015a) I show that the halo mass history is well described by an exponential function of redshift in the high-redshift regime. However, in the low-redshift regime the mass history follows a power law because the growth of density perturbations is halted in the dark energy dominated era due to the accelerated expansion of the Universe. I then provide an analytic model that depends on cosmology and on the linear matter power spectrum. In Correa et al. (2015b) I explore the relation between the structure and mass accretion histories of dark matter halos using a suite of cosmological simulations. I then provide a semi-analytic model for halo mass history that combines analytic relations with fits to simulations. The model depends on halo concentration and formation time. Find out more in Correa et al. (2015a) here and Correa et al. (2015b) here.