A study to find patterns of cohesion and rhetorical structure that distinguish good from weak English essay writing is described. The corpus consisted of ten Swedish college essays written as part of the final exam in a first-year English course. Methodological problems encountered included the delimitation of units for the analysis of cohesive ties, establishment of categories of cohesive ties, and delimitation of the size of the cohesive item itself. The results support the hypothesis that cohesive tightness, measured by the proportion of cohesive ties, is a sign of good quality writing. The good essays contained a greater proportion of hyponymy/hyperonymy and specification/generalization ties, suggesting that weaker writers have more difficulty in moving from one level of generality to another. Good essays also contained fewer instances of two types of lexical ties, identity (repetition) and ellipsis, and cohesive relations signalling the specific logic of reasoning differed in the good and weak essays. While the corpus used is too small to allow detection of specific error patterns in sentence connectors, the findings do suggest that coherence should be studied from the perspective of levels of generalization and the functional relations between units. (MSE)