This study of 1,974 fifth grade students investigated potential relationships between writing process-based instruction practices and higher-order thinking measured by a standardized literacy assessment. Writing process is defined as a highly complex, socio-cognitive process that includes: planning, text production, review, metacognition, writing for comprehension, and a social context. Writing process-based instruction was measured through teacher-reported instructional log data. Higher order literacy achievement is defined according to the average cognitive demand of the groups of test items comprising the subscales of the "TerraNova" assessment. Although prior research suggested otherwise, this study yielded little evidence of conditional relationships between writing instruction and literacy achievement. This study also produced little evidence that students in the sample experienced writing process-based instruction on a regular basis as defined here. That lack of exposure may partly explain the lack of evidence of relationships between writing instruction and student literacy achievement outcomes. Finally, the "TerraNova" assessment had limitations as a measure of higher order thinking. New assessments such as Smarter Balanced may be better suited to future studies of relationships between students' experiences with writing process-based instruction and their achievement in higher order literacy skills. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]