Self-regulation has a positive impact on learning and academic achievement, but due to its nature, it is difficult to assess it in a valid and reliable manner. This study aims to explore the validity of three self-regulation assessment methods in text comprehension tasks (questionnaire, think-aloud and traces) as well as to identify the variables associated with reading performance. For this purpose, individual sessions were conducted with 96 sixth-grade primary education students, who were asked to read a text and complete two reading comprehension tasks working in a virtual environment. Task traces were recorded, think-aloud was recorded and coded, and participants answered a self-report questionnaire about the strategies used. A limited relationship was found between self-regulation measured by means of the questionnaire, think-aloud and traces, and the relationship between think-aloud and traces was moderate. Regarding the factors related to text comprehension task performance, think-aloud and task time measurements were found to be better predictors of performance than the questionnaire.