Future galaxy spectroscopic surveys will make high precision measurements of the clustering of galaxies on scales in excess of 100 Mpc/h. In particular, the distortion of clustering due to the peculiar motions of galaxies and the apparent scale of characteristic features in the galaxy distribution have been proposed as tests of the cosmic acceleration. To obtain meaningful and robust constraints on dark energy, we need to understand any systematics in these measurements. I will present the predictions for redshift space distortions from large volume N-body simulations and discuss the accuracy of current models in recovering the growth rate. In addition I will show predictions of the clustering of dark matter in redshift space in f(R) modified gravity and in quintessence dark energy cosmologies.Due to the size and resolution of these simulations, this is the first time that the nonlinear matter and velocity fields in this class of modified gravity models has been resolved to a high level of accuracy over a broad range of scales. I will also discuss a galaxy infall kinematics model which, in combination with weak lensing measurements, can provide powerful diagnostics of modified gravity.