A new method is described for the measurement of Young's modulus and its variation with temperature below 400\ifmmode^\circ\else\textdegree\fi{}C. The method is applied to single crystals of pure nickel and to hard drawn, polycrystalline, commercial nickel between 30\ifmmode^\circ\else\textdegree\fi{}C and 400\ifmmode^\circ\else\textdegree\fi{}C. The variation of Young's modulus with temperature in these substances depends on the previous thermal history of the sample. Between 30\ifmmode^\circ\else\textdegree\fi{} and 200\ifmmode^\circ\else\textdegree\fi{} Young's modulus for annealed specimens decreases about 13 percent. This is followed by an increase to the Curie point of about 6 percent and above the Curie point by a linear decrease. For hard drawn specimens and specimens quenched at 1100\ifmmode^\circ\else\textdegree\fi{} the minimum is wholly absent. Young's modulus decreases continuously to the Curie point, where the temperature coefficient changes abruptly.