Research findings regarding speech errors made by second language learners and affective reactions to native speakers as a basis for error correction are considered. A research design is presented for investigating sensitivities to 15 types of grammatical errors typically made in speech by American learners of French. Findings of the research are summarized and compared to data available in Spanish, German, and English. Research findings concerning teaching evaluation of French grammatical errors as compared with native speaker evaluation of the same errors are also presented, and a pedagogical error hierarchy for French is suggested as a means by which this hierarchy might be used in syllabus design, the selection of instructional methodology, and the creation of classroom error correction strategies. Judges included native French speakers tested in France and teachers of French tested in the United States. Native French speakers came from Paris and Nancy and included three age groups: middle school and high school students and adults. For adults and high school students, the following hierarchy of errors was revealed, from most to least irritating: verbs, pronouns, definite articles, prepositions, and adjectives. Similar findings for Spanish, German, and English have been reported. Overall it was found that affective reaction to error varied according to the age of the judge. It is proposed that correction be reserved for errors that are known to cause negative reaction among native speakers. (SW)