In this paper, three new
characterizations of uniform convexity of a Banach space X are established. The
characterization developed in Theorem 1 resembles the definition of the modulus of
smoothness given by J. Lindenstrauss. The characterizations developed in Theorems
2 and 3 are interrelated, both involving the duality map of X into X∗. The methods
used are adapted to give an abbreviated proof of a recent result of W. V.
Petryshyn relating the strict convexity of X to the duality map of X into
X∗.