This study explored the extent to which the ethnic identity of a writer and the background (gender and area of teaching) of a rater can influence mainstream teacher candidates' evaluation of English as a second language (ESL) writing, using a matched-guise method. A one-page essay was elicited from an ESL learner enrolled in an intensive English program and was manipulated to incorporate error patterns often observed among Chinese- and Spanish-speaking learners. Teacher candidates were led to believe it was produced by an ESL learner whose first language was either Chinese or Spanish. One-hundred-sixty-three undergraduate students enrolled in a teacher education program at a U.S. university were asked to score the ESL essay holistically, provide qualitative comments, identify the three most troublesome errors in order of seriousness, and offer advice on how to improve ESL writing. No significant effects of writer identity on the holistic scoring were detected, but the teacher candidates revealed different categories of rater responses depending on the writer's identity. Conversely, although the raters' backgrounds (gender and area of teaching) had significant effects on global scoring, they did not have any significant impact on the qualitative nature of rater responses.