I was recently introduced to Soir de fete by Enerst Chausson (Op.32) by an excellent recording made by Orchestre De La Suisse Romanda and Marek Janowski (PentaTone Classics). I went searching for the sheet music for community orchestra here at IMSLP, Kalmus, and di-arrezzo, and there is no sign of it.
Given the age of the composition (1897-1898), it may be a safe bet this is public domain and would make an excellent addition to IMSLP should someone out there have the orchestra parts.