This article delves into composer Camargo Guarnieri's interaction with Pan-Americanist thinking in 1940s Brazil and its impact on his compositions, particularly focusing on Improviso No. 2 for solo flute. Amid intercontinental unity ideals, Guarnieri's connections with U.S. cultural envoys Carleton Sprague Smith and Aaron Copland influenced his works. Examining Improviso No. 2 through Topic Theory, the study unveils the rhythmic elements reflecting Guarnieri's immersion in the Latin Americanist environment fostered by his American contacts. Overlooked archival sources, including Smith's and Copland's reports and correspondence, enrich the analysis, providing insights into Guarnieri's musical choices and experiences within the cultural exchange landscape. The article contributes to a deeper understanding of Guarnieri's music and its ties to Pan-Americanist ideals, shedding light on a lesser-known facet of his compositional output.