This study investigated the constructs of reading motivation (i.e., affective and cognitive reading attitude, and reading self-concept) and examined their relations with reading behavior and performance. Hong Kong data from PIRLS 2016 were analyzed to address the questions. A special attention was paid to the indirect influences of the motivational constructs on reading performance via the influence of reading amount. Results confirmed that reading attitude could be further distinguished into the affective and cognitive components. These components of reading attitude along with reading self-concept were demonstrated to have differential relations with reading amount and achievement. Results also found significant relations between reading attitude and reading self-concept on one hand, and reading achievement on the other hand mediated by reading amount.