Unlike your undergraduate applications, where you may have had numerous essays to write, generally you will only have one written shot at telling the admissions committee about your interests when completing the graduate application.  Your essay must be seamless. 

Be prepared to summarize your research and coursework in a way that clearly demonstrates your preparation for graduate work in your field.  You will need to evince a level of articulation about your field that suggests to the faculty evaluating your application that you are serious and on the up-and-up about fully devoting yourself to the academics.  You will also have to show a fair level of knowledge about the faculty and their research interests, even going so far as to posit one or two faculty as possible research supervisors, especially if you have met with them (or had them as professors).

We at Entablature will take care in making sure that your essay reflects all of the above.  It may take several rounds, but in the end, the blood, sweat and tears will have been worth it!