This is the first volume of two of what is by many considered the definitive biography of James Boswell. This first volume was published in 1966, written by the foremost Boswellian scholar of the 20th century, the longtime editor of the Yale Boswell papers, Frederick Pottle. The volume covers Boswell's life from his birth in 1740 until his marriage with Margaret Montgomerie in 1769. It was followed in 1984 by a second volume (The Later Years), written by Frank Brady, detailing his life as a married man and - later - a widower and author of the Life of Johnson, ending with his death in May 1795.
Compared to other biographies about Boswell, this two-volume series is at the same time well written and thoroughly annotated. This first volume contains more than 100 pages of extensive endnotes.
Those looking for a more condensed, noteless but still major biography should probably go for Peter Martin's A Life of James Boswell instead.
James Boswell: The Earlier Years has been reprinted at least once, in 1985, and is always available from various bookstores via AbeBooks.