We know from Quantz that in Baroque times cellos appeared in at least two sizes.1 In this thesis all aspects of the smaller instrument are examined. Tunings to F or G, as specified by relevant theoretical writings from the Renaissance and Baroque periods, indicate that small cello-type instruments between the sizes of violas and cellos are likely to have been used from the beginning of violin building. Measurements for such instruments were not specified either by theorists or commentators. This gap is filled here by measuring and documenting a relatively large number of surviving examples. Iconographical representations are discussed, as they indicate that the small instrument might have preceded the bigger cello. Of the smaller instruments, those in size between the viola and the cello, the focus is on the G-tuned instrument and on the music which might have been or, arguably, should have been played on it. Repertoire examined by Baroque as well as later composers throughout Europe strongly suggests that the G-tuned instrument was used but rarely specified. On the evidence of current findings, the instrument was mostly referred to as a cello or small bass violin (although occasionally as tenor violin, violoncello piccolo and by other terminology). Its survival would have been smoother - fewer of these instruments would have been turned into childs cellos - if it had been called the tenor cello. 1 Johann Joachim Quantz, Versuch einer Anweisung die Flote traversiere zu spielen, Berlin, 1752, 212.