在使用引號時，美國人習慣使用雙引號 (double quotation marks)，而英國人使用單引號 (single quotation marks)。例如：
- John said that he was “very angry.” (約翰說他「很生氣」) (正)
- John said that he was ‘very angry’. (正)
因此，就美式英語而言，一般都是先使用雙引號，若該引號內還需要引號，則使用單引號。例如：
- Julian asked me: “Would you like to see ‘Fast & Furious 7’?” (朱利安問我：「你想看《玩命關頭7》嗎？」) (正)
- Mary asked Henry: “Do you have lyrics to ‘Radioactive’ by Imagine Dragons?” (瑪麗問亨利：「你有 Imagine Dragons 樂團所唱的《Radioactive》的歌詞嗎？」) (正)
- The professor said: “This course uses two books. The first is Howard Jackson’s ‘Lexicography’ and the second is ‘Language Assessment’ by H. Douglas Brown.” (教授說：「本課程使用兩本書。第一本是 Howard Jackson 所著的《Lexicography》，第二本是 H. Douglas Brown 所著的《Language Assessment》」) (正)
- The professor said: “This course uses two books. The first is Howard Jackson’s “Lexicography” and the second is “Language Assessment” by H. Douglas Brown.” (誤) － 將這句標示錯誤是有點嚴苛，因為有些人認為這樣也可以。
然而，大家一致公認的規則是，在同一層級，單引號和雙引號不可混合使用。例如：
- The professor said: “This course uses two books. The first is Howard Jackson’s ‘Lexicography’ and the second is “Language Assessment” by H. Douglas Brown.” (誤)
註：在句子中，書籍、報紙、雜誌、報告、文學與藝術作品、詩詞、戲劇、電影和電視節目的名稱，通常以引號或斜體字來區隔。因此，上述的 Fast & Furious 7、Lexicography 和 Language Assessment 亦可用斜體字而不用引號，即 Fast & Furious 7、Lexicography 和 Language Assessment。
相對地，就英式英語而言，一般都是先使用單引號，若該引號內還需要引號，則使用雙引號。例如：
- Julian asked me: ‘Would you like to see “Fast & Furious 7”?’ (正)
- Mary asked Henry: ‘Do you have lyrics to “Radioactive” by Imagine Dragons?’ (正)
由於英美的引號用法並不一致，著名的文體指南有的建議雙引號內使用單引號，有的則建議單引號內使用雙引號。不過，視寫作者的個人偏好而定，不管採用何種寫法，整篇文章或整份文件須保持一致。例如：
- Does anyone know what the difference between “soon” and “when” is? (有人知道「soon」和「when」之間有什麼不同嗎？) (正)
- Does anyone know what the difference between ‘soon’ and ‘when’ is? (正)
- Does anyone know what the difference between “soon” and ‘when’ is? (誤)