Research investigating affective dimensions in reading has long been plagued by vaguely defined constructs and, consequently, by an array of potentially problematic instruments designed to measure them. This mixed-methods study investigated the relationship among three popular group-administered instruments intended to tap affective constructs in reading. Participants included nearly 500 fourth- and fifth-grade students enrolled in four schools in a Southern state. During two testing sessions, the students completed the Elementary Reading Attitude Survey (ERAS), the Motivation to Read Profile (MRP), the Reading Self-Concept Scale (RSCS), and a reading comprehension measure, the Gray Silent Reading Test (GSRT). Following quantitative analyses, qualitative research commenced with a subsample of 16 participants. Twelve survey items suspected of inviting misinterpretations by students were examined through cognitive interviews. This subsample was also asked questions about factors unaccounted for in the surveys. The three affective measures comprised seven subscales, all of which correlated with one another, with and without controlling for comprehension. Regression analysis indicated that four of the subscales together accounted for 32% of the variance in comprehension. Suspected overlap in the constructs assessed by the subscales led to confirmatory factor analyses, which indicated that the seven subscales were represented best by two factors: self-beliefs and attitudes. These factors together accounted for slightly less variance (22%) in comprehension scores than the four subscales used in the initial analysis. Possible differences between these two factors was next analyzed through multivariate analysis of covariance, with comprehension a covariate. This analysis revealed significant differences for both gender and ELL status, but not for ethnicity or for any of the interactions. Follow-up tests suggested that females held higher attitudes towards reading than did males (even when comprehension proficiency was controlled) and that students who are English language learners had lower self-beliefs than students who were not. Cognitive interviews indicated that 8 of the 12 items were problematic and that these items fell into three problem types: terminological, situational, and logical. Conversational interviews suggested additional affective issues not tapped by the surveys. The interviewees indicated that family members (particularly mothers) remained primary influences, that vocabulary in texts was perceived as the greatest challenge, and that students remained skeptical of reading online sources. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]