WR stellar wind sweeps up mass lost from the star at an earlier epoch. Ejecta shells tend to be small ($\sim$5-10 pc in radius; Chu 1981; Marston 1997), and are generally identified chemically by high nitrogen-to-oxygen ratios (indicative of CNO processing). The W-type shells ($\sim$10-20 pc in radius) are produced when a strong WR stellar wind sweeps up ambient interstellar medium. Some Galactic WR stars have been observed to exist within shells (Arnal 1992). Eventually WR stars undergo a supernova explosion at the end of their lives. WR stars, therefore, have a substantial impact on their surroundings during the various phases of their evolution.

We present the results of an ongoing study focusing on the interaction of massive stars with the ISM, in nearby galaxies, from single stars to associations (see Thilker, Braun, & Walterbos 1998). Together, these investigations provide a detailed view of the processes by which massive stars shape the surrounding ISM, from pc to kpc scales. The main goal of this paper is to study the environments of WR stars to find evidence for WR wind-ISM interactions in M31, through imaging ionized hydrogen nebulae surrounding these stars.

We have conducted a systematic search for nebulae near WR 