A formal analytical approach was utilized to develop chart analyses of all movements within 33 selected piano concertos composed in the twentieth century. The macroform, or overall structure, of each movement was determined by the initial statement, frequency of use, and order of each main thematic element identified. Theme groupings were then classified under formal classical prototypes of the eighteenth and nineteenth centuries (ternary, sonata-allegro, 5-part or 7-part rondo, theme and variations, and others), modified versions of these forms (three-part design), or a variety of free sectional forms. The chart and thematic illustrations are followed by a commentary discussing each movement as well as the entire concerto. No correlation exists between styles and forms of the 33 concertos--the 26 composers use traditional, individualistic, classical, and dissonant forms in a combination of ways. Almost all works contain common unifying thematic elements, and cyclicism (identical theme occurring in more than 1 movement) is used to a great degree. None of the movements in sonata-allegro form contain double expositions, but 22 concertos have 3 movements, and 21 have cadenzas, suggesting that the composers have largely respected standards established in the Classical-Romantic period. Appendix A is the complete form diagram of Samuel Barber's Piano Concerto, Appendix B has concentrated analyses of all the concertos, and Appendix C lists each movement according to its design. (WM)