It is generally agreed that the most effective method of assessing written language is through spontaneous writing samples. The purpose of this study was to compare the results of measures of written language that utilize a spontaneous writing sample. The Wechsler Individual Achievement Test (WIAT) Written Expression subtest is of particular interest as there is only minimal information on this measure and little research is as yet available. As such, this study compares results of the Written Expression subtest of the WIAT with the Written Expression subtest (Level II) of the Peabody Individual Achievement Test - Revised (PIAT-R) and with the Spontaneous Writing Quotient of the Test of Written Language -2 (TOWL-2) in order to provide information specific to the concurrent validity of these measures. Pearson-product moment correlation coefficients indicated that the WIAT Written Expression subtest correlates moderately with both the Written Expression subtest of the PIAT-R and the Spontaneous Writing Quotient of the TOWL-2. Implications of these findings in the assessment of written language are discussed.