We study the dynamics of inflation driven by an adiabatic self-gravitating medium, extending the previous works on fluid and solid inflation. Such a class of media comprises perfect fluids, zero and finite temperature solids. By using an effective field theory description, we compute the power spectrum for the scalar curvature perturbation of constant energy density hypersurface $\zeta$ and the comoving scalar curvature perturbation ${\cal R}$ in the case of slow-roll, super slow-roll and $w$-media inflation, an inflationary phase with $w$ constant in the range $-1 Comment: 31 pages, 1 figure. A number of typos corrected, improved discussion of reheating