  We use the Heegaard-Floer homology correction terms defined by
Ozsv\'{a}th--Szab\'{o} to formulate a new obstruction for a knot to be of
finite order in the smooth concordance group. This obstruction bears a formal
resemblance to that of Casson and Gordon but is sensitive to the difference
between the smooth versus topological category. As an application we obtain new
lower bounds for the concordance order of small crossing knots.
