The feasibility of using linear and equipercentile equating methods to equate forms of the TWE® (Test of Written English™) by using the TOEFL® test as an anchor was explored. These two equating methods assume that either the TOEFL test and TWE test measure the same skills or that the examinee groups across TWE administrations are equivalent in skills. The differences between equated and observed scores (equating residuals) and differences among the mean equated scores for examinee groups were further examined in terms of characteristics of the TWE topics. An evaluation of the assumptions underlying the equating methods suggests that the TOEFL and TWE tests do not measure the same skills and that examinee groups are often dissimilar in skills. Therefore, use of the TOEFL test as an anchor to equate TWE tests does not appear appropriate. An alternative equating model based on expert judgment during pretest evaluation of potential essay prompts is recommended for future investigation.