Two factors which may affect the ratings assigned to an essay test are investigated: (1) context effects; and (2) score level effects. Context effects exist in essay scoring if an essay is rated higher when preceded by poor quality essays than when preceded by high quality essays. A score level effect is defined as a change in the score (value) assigned to the second reading of an essay when compared to the first reading, where the change is a function of the range in which a score may increase or decrease. The potential dual effect of both these factors is theorized in a formula called the essay score change. Examples of the possible utility of this index are outlined. Tentative hypotheses for investigating and interpreting possible essay score change in light of potential dual effects of context and score level are discussed. (Author/GDC)