I review the constraints on standard big bang model arising from consi
derations related to structure formation. I will focus on two specific
series of models though similar analysis can be performed for a wider
class of models. The first one is a Ohm = 1 model with non-zero cosmo
logical constant and the second one is a Ohm < 1 model with zero cosmo
logical constant. The observational constraints which I shall discuss
include the measurement of the Hubble's constant, the ages of globular
clusters, the abundance of rich clusters, the baryon content of galax
y clusters and the abundance of high redshift objects. These constrain
ts limit the allowed range of the cosmological parameters and allow fo
r only a small region to survive. In particular, the aesthetically ple
asing model with Ohm = 1 and zero cosmological constant is ruled out b
y the observations. It seems necessary to fine-tune the theoretical pa
rameters if they have to fall within the available space. This talk is
based on the work in Bagla et al. (1996).