While 85% of the Universe is made of dark matter, the knowledge of its distribution
within cosmic structures such as galaxies or clusters of galaxies is essential for two reasons:
1) it provides the baseline against which one can measure many astrophysical properties, such as
the gas and stellar content of cosmic structures; 2) it distinguishes between various
predictions obtained from cosmological simulations without and with gas. Focussing on measuring
the dark matter distribution in quasi-spherical systems using kinematical tracers, I will
discuss the degeneracy between the unknown radial distributions of total mass and velocity
anisotropy, inherent in the Jeans equation of local equilibrium. I will highlight the many
methods to handle this "mass-anisotropy" degeneracy,  including three new ones that I developed
or co-developed. I will then apply these methods to
clusters of galaxies, groups of galaxies, elliptical galaxies and dwarf spheroidals. Some
surprising results then emerge.