Dear Mr. Henshaw is deary's most serious work, and many critics consider it her best. It is clearly a departure in format, style, content, and tone from her usual lighthearted books. The exclusive use of journal entries and letters to Mr. Henshaw makes the novel unique among Cleary's works. This "epistolary" technique was first used in Samuel Richardson's Pamela (1740). The only details provided about Leigh, his life, and his family are those revealed in his own letters and diary. The result is a very personal story that seems almost like an autobiography; the reader easily relates to Leigh as he bares his thoughts and feelings through his writing.

With charming style, Cleary conveys Leigh's immaturity in his early letters.

Common misspellings ("Keep in tutch") and improper word usage ("I am a great enjoyer of your books") at once amuse the reader and make the character likable...