  I consider the growth of inhomogeneities in a low-density baryonic, vacuum
energy-dominated universe in the context of modified Newtonian dynamics (MOND).
I first write down a two-field Langrangian-based theory of MOND
(non-relativistic), which embodies several assumptions such as constancy of the
MOND acceleration parameter, association of a MOND force with peculiar
accelerations only, and the deceleration of the Hubble flow as a background
field which influences the dynamics of a finite size region. In the context of
this theory, the equation for the evolution of spherically symmetric
over-densities is non-linear and implies very rapid growth even in a
low-density background, particularly at the epoch when the putative
cosmological constant begins to dominate the Hubble expansion. Small comoving
scales enter the MOND regime earlier than larger scales and therefore evolve to
large over-densities sooner. Taking the initial COBE-normalized power spectrum
provided by CMBFAST (Seljak & Zeldarriaga 1996), I find that the final
power-spectrum resembles that of the standard LCDM universe and thus retains
the empirical successes of that model.
