Co-authored by Chauncey Brewster Tinker and his former doctoral student Frederick A. Pottle, A New Portrait of James Boswell is an iconographical monograph establishing the provenance and attribution of the earliest known oil portrait of James Boswell, painted in Rome in the spring of 1765 by the Edinburgh artist George Willison (1741-1797) and housed in the Scottish National Portrait Gallery (bequeathed by Captain James Wood in 1912).

Before this study, the best-known lifetime likenesses of Boswell dated from his middle and later years, most notably the 1785 oil portrait by Sir Joshua Reynolds, the 1793 profile drawing by George Dance the Younger, and the sketches by Sir Thomas Lawrence and George Langton. Using documentary evidence from Boswell's Italian correspondence and memoranda from his Grand Tour in Italy, Tinker and Pottle demonstrated that the canvas in the Scottish National Portrait Gallery (depicting a twenty-four-year-old Boswell in a scarlet-and-yellow waistcoat and fur-trimmed green coat against a nocturnal background with an owl perched overhead) was the painting Boswell commissioned from his fellow Scot George Willison in Rome in May 1765.

In addition to its frontispiece in colour reproducing the Willison canvas, the volume contains nine monochrome plates and a critical survey of all known and putative portraits, drawings, busts, and caricatures of Boswell, serving as the standard study of Boswell's portraiture prior to modern iconographical catalogues.