Theme and Variations is arguably one of the oldest musical forms in music history. Composers have used certain themes repeatedly as thematic sources for variations. Among them, Paganini's Caprice No. 24 in A minor is certainly the best known, since the theme has inspired many composers for variations of their own. The purpose of this study is to analyze different sets of Variations on Paganini's theme by Franz Liszt, Witold Lutoslawbski, Johannes Brahms, and Sergei Rachmaninoff, in order to examine, identify, and trace how far an original idea can be stretched by using different variations techniques and their applications. Liszt transcribed Paganini's 24th Caprice for the piano, adding a multi-layered sound to the original Caprice. His treatment of the Paganini theme is the most literal. Lutoslawski's Paganini Variations is written for duo piano. This piece builds on Liszt's transcription technique: it stays close to the original Paganini Caprice, but at the same time overlays many 20 th century compositional devices such as atonality and complex rhythmic devices. Lutoslawski carries Liszt one step further away from Paganini's original theme. In his Variations on a Theme of Paganini, op. 35, Brahms keeps the clear structure and strong harmonic progression of the original theme, but carries his invention further away from the source than Liszt and Lutoslawski. His compositional technique includes adding new harmonies within the harmonic structure, marking different tempo indications and meter changes, playing with a variety of rhythm and motives, as well as accentuating the harmonic progression and the bass progression. Rachmaninoff's Rhapsody on a Theme of Paganini, Op. 43 is the most personal. He places greater emphasis on the melodic and motivic elements of the theme, and nearly exhausts every option of transformation. Rachmaninoff's extensive development represents the furthest point away from Paganini's source.