  Inflation is studied in the context of induced gravity (IG) $\gamma \sigma^2
R$, where $R$ is the Ricci scalar, $\sigma$ a scalar field and $\gamma$ a
dimensionless constant. We study in detail cosmological perturbations in IG and
examine both a Landau-Ginzburg (LG) and a Coleman-Weinberg (CW) potential toy
models for small field and large field (chaotic) inflation and find that small
field inflationary models in IG are constrained to $\gamma \lesssim 3 \times
10^{-3}$ by WMAP 5 yrs data. Finally we describe the regime of coherent
oscillations in induced gravity by an analytic approximation, showing how the
homogeneous inflaton can decay in its short-scale fluctuations when it
oscillates around a non-zero value $\sigma_0$.
