In this bachelor project, Leon Falk has examined the interplay and collective improvisation in New Orleans jazz and related genres - in particular the interplay among the wind instrumentalists in New Orleans jazz and brass bands. The main goal has been to develop as a trombone player and ensemble musician.This reflective thesis includes a description of the process of the project and the exam concert, a historical reflection about the New Orleans jazz and brass band tradition and an analysis of 9 interviews with contemporary musicians playing traditional jazz: Jens "Jesse" Lindgren, Björn Ingelstam, Ulf Johansson Werre, Joakim Falk, Claes Ringqvist, Klas Lindqvist, Hans Ingelstam, Niklas Carlsson and Örjan Kjellin. The thesis ends with a conclusive reflection about the project as a whole and Leon Falk's own play style in ensemble with other wind instruments.