The goals of the current study were to develop domain-specific measures of reading and writing achievement motivation that could be used with students at different grade levels in both intervention studies and developmental research. We framed motivation to read and write in terms of goals and definitions of success to address limitations of current measures by focusing on children's reasons or motives for learning or improving reading and writing skills. We used achievement goal theory to develop and test scales measuring achievement motivation (orientations) in reading and writing with a longitudinal sample of students in grades 2, 4, and 5 (Cohort 1) and 4, 6, and 7 (Cohort 2). Multiple-group confirmatory factor analyses provided evidence of congeneric grade invariance for reading scales including two dimensions of task orientation (mastery and interest), reading ego orientation and reading avoidance/alienation. More complex results supported congeneric grade invariance of writing scales for two dimensions of task orientation (social communication, creative self-expression), writing ego orientation, writing avoidance/alienation, and either ego-avoidance (4th & 5th grades) or writing mastery orientation (6th & 7th grades). Concurrent and discriminant validity were demonstrated through positive correlations between task orientation factors and measures of reading and writing attitude, and negative correlations between reading and writing avoidance and performance on the WIAT II. Reading and writing motivation scales were correlated in ways consistent with previous cross-domain research using achievement goal theory. Implications for developmental and intervention research in reading and writing are discussed. (C) 2013 Elsevier Inc. All rights reserved.