  Hierarchical Lambda CDM models provide a successful paradigm for the growth
of dark matter on large scales, but they face important challenges in
predicting how the baryonic components of galaxies evolve. I present
constraints on two aspects of this evolution: (1) The interaction history of
galaxies over the last 7 Gyr and the impact of interactions on their star
formation properties, based on Jogee et al. (2008a,b); (2) Constraints on the
origin of bulges in hierarchical models and the challenge posed in accounting
for galaxies with low bulge-to-total ratios, based on Weinzirl, Jogee, Khochar,
Burkert, and Kormendy (2008, hereafter WJKBK08)
