There is an increasing focus on formative assessment as education systems all over the world try to incorporate 21st-century skills in their curriculums. Formative assessment has been considered one of the best approaches to teaching and assessing 21st-century competencies, which are crucial in addressing the current economic challenges. This review of thirty-eight empirical studies was done to find out how the key strategies of formative assessment have been conceptualized and their effect on students' motivation, engagement, and achievement. The analysis revealed that some strategies like the use of discussion have not been studied empirically. Other strategies such as learning intentions, success criteria, and selfassessment have only been used to a lesser extent. The analysis showed a positive influence of formative assessment strategies on students' motivation, engagement, and achievement. The results of this analysis provide a roadmap in the advancement of the theory of formative assessment and direction for future inquiry.