The current paper on writing assessment surveys the literature on the reliability and validity of essay tests. The paper aims to examine the two concepts in relationship with essay testing as well as to provide a snapshot of the current understandings of the reliability and validity of essay tests as drawn in recent research studies. Bearing in mind that essay tests are the most crucially and widely used direct writing assessments worldwide, our research is driven by the fact that successful implementation of assessment practices depends on an understanding of reliability and validity. The review focuses primarily on the general theoretical and practical aspects of reliability and validity and particularly on the evolution within and the relationship between the two concepts. Aspiring to synthesize research findings about the validity and reliability of essay exams as a means of direct testing of writing, we focus on the three main axes raters, scoring scales, and the prompt of an essay test. The results would inform test developers and language testing researchers about the current status and future directions of writing assessment research. Research of this kind is needed so that a fuller understanding of the validity and reliability of essay exams is achieved.