This questionnaire study analyzed responses of 96 first-, second-, third-, and fourth-year students of College German to the second part of a two-part question, namely, (a) what forms of German grammar are particularly difficult, and (b) why so. Response patterns show that word order, adjective endings, the subjunctive, and the gender/number/case complex were found to be particularly challenging. Students' explanations of difficulty predominantly referred to the nature of "rules" (their complexity, number, opacity--or absence, such as in "exceptions") and the role of memory, especially memorization. Memorization is named as important by learners in all four years of study but becomes less prominent at the higher levels. Further, explanations differed according to the form under discussion. Memorization figured particularly prominently into explanations of why gender/case/number forms are difficult whereas rule complexity was the leading explanation for the challenges of word order and rule opacity for difficulties with the subjunctive. A lack of frequency of occurrence of or meaningful practice with forms featured only marginally. Students' responses imply a mechanistic view of language learning that deviates from both current research and pedagogy.