  The inner detector is the central tracking device of the ATLAS detector. In
these proceedings the tracking performance of the inner detector is presented
on collision data recorded at $\sqrt{s}$ = 900 GeV and 7 TeV. The
identification of resonances like $\Xi$ and $\Omega$ baryons in cascade decays
via $K_{\mathrm{s}}$ and $\Lambda$ mesons is presented as well as the
reconstruction of the $J / \psi $ and $\psi$(2S) mesons decaying into two
muons. Furthermore, the performance of the track reconstruction and a
data-driven method of estimating the track reconstruction efficiency as used in
measurements of charged particle densities are discussed.
