The most interesting thing about Mary McCarthy's autobiographical work, to me, is not her tragic orphanhood and unhappy childhood among oppressingly religious relatives and grandparents, but rather her method of writing. The novel includes not only short stories and collections of anecdotes from her early years, but each one is followed by a brief commentary, analysing her methods and the process of remembering, the unreliability of memory, and the fictionalisation of certain sections for the sake of filling gaps or dramatising.
Personally, I find it fascinating that an autobiographer (and especially someone who is also a fictional writer and well-known novelist) is willing to elaborate and explain her personal writing technique so openly. She readily confesses that she does not remember everything, or is not sure what really happened, who is telling the truth and so on. She also reveals which parts in her autobiographical sections are fictional, or simply events that "could have happened, but didn't really". While some readers may find that this explicit, detailed honesty ruins their reading experience, it should be remembered that autobiographies should not and cannot be read in a similar, escapist way to fictional novels. Usually they aim, at least to some extent, for a realistic, historically accurate depiction of what really happened - a task which is obviously made more difficult due to the subjective, selective and unreliable nature of memory, and the impossibility of recalling let alone telling "everything".
In Mary McCarthy's case, the problems of memory and reconstructing the past are even more concrete. Both her parents died within days of each other when she was very young and her grandparents and relatives rarely spoke of them (or anything related to personal history for that matter). McCarthy attempts to wade her way through her misty childhood atmosphere of secrecy and silence to find out as much as she can about a past she feels she doesn't truly possess and an identity with no existing origins.
Mary McCarthy: Memories of a Catholic Girlhood. Penguin Books. 1957.
Links:
NY Times review: Memories of a Catholic Girlhood
Authors' calendar: Mary McCarthy
Buy Memories of a Catholic Girlhood from The Book Depository


