Strategy interventions have been found to support students' text comprehension, but little is known about the sustainability of these effects. This study examined short- and long-term effects of a strategy intervention on students' vocabulary and text comprehension at the literal, inferential and evaluative levels. A pretest, posttest, and retention test design with experimental and control conditions was used. Ninety-nine six-graders from six Estonian schools were examined while using vocabulary and text comprehension tests. Comprehension strategies were taught in an experimental condition by Estonian-language teachers during a three-month intervention. The group-level analysis indicated short-term improvements in all skills when strategies were taught. The long-term effect was found in literal and inferential comprehension with continual improvements in literal comprehension. For the students in the control condition, short- and long-term improvements were detected in literal text comprehension. The individual-level analysis revealed three vocabulary and text comprehension profile groups: Average High, Average Low, and Low Combined. In the experimental condition, students from every profile group benefited from the intervention. In the control condition, enhancements were seen in the students in the Average High profile group. Thus, the explicit teaching of comprehension strategies supports students in becoming aware of using multiple comprehension strategies, despite individual differences.