State-to-state rotational energy transfer of ground state NH(X (3)Sigma(-),v=0,J,N) in collisions with He and N-2 is studied. A complete inversion between the metastable NH(a (1)Delta) state and the NH(X (3)Sigma(-)) state is generated via the photodissociation of hydrazoic acid at a wavelength of 266 nm. Single state NH(X (3)Sigma(-),v=0,J,N) is generated by applying the stimulated emission pumping technique using the strongly forbidden NH(a (1)Delta-->X (3)Sigma(-)) intercombination transition around 794 nm. The ground state NH(X (3)Sigma(-),v=0,J,N) distribution is probed with respect to all quantum states using laser induced fluorescence varying delay times and pressures. The collision induced energy transfer between the different rotational and spin levels is extensively studied and two comprehensive sets of rate constants for vibrationally elastic and rotationally inelastic collisions with He and N-2 as collision partners are given which include the effect of multiple collisions. We find propensities for (DeltaN=0,Deltai=+/-1) and (DeltaN=+/-1,Deltai=0) transitions where N represents the quantum state for nuclear rotation and i represents the index of the spin component F-i. The rotational relaxation for N-2 as a collision partner occurs on the average three times faster than the rotational relaxation with He as a collision partner. The energy dependence of the transition efficiency for only the nuclear rotational quantum number N obeys an energy-gap law for both He and N-2.