This study investigated what features undergraduate EFL learners perceive as affecting the difficulty of model paragraphs. Four hundred and seventy-five Vietnamese undergraduates participated in a partial least squares structural equation model design. They ranked five paragraphs from easiest to most difficult and responded to a 10-point Likert questionnaire regarding 11 features (titles, paragraph length, vocabulary, vocabulary in context, rhetorical organization, paragraph structure, sentence length, punctuation, signal words, interest, background knowledge). The results showed that eight variables (titles, vocabulary, vocabulary in context, sentence length, rhetorical organization, paragraph structure, interest, background knowledge) had a significant direct effect and four variables (vocabulary, sentence length, rhetorical organization, background knowledge) had mediating effects. The model accounted for 0.508 R[superscript 2] of students' perceptions, with a moderate to high predictive relevance (Q[superscript 2] = 0.35). The paper also discusses the results' implications for those in writing studies and the publishing industry. Suggestions for future study are also presented.