Now in his 21st season as a bass-baritone with the Arizona Opera Chorus, Mark has sung in 59 productions. Arizona Opera is a regional company which mounts four productions a year (five beginning in 1995/1996). Each show is performed 2-3 times in Tucson and then is moved to Phoenix where it is performed 4-5 times. Performances are in original languages (usually Italian, French, and German) with supertitles projected above the stage in English. The chorus consists of professional musicians and rehearses ten months out of the year. More than 90% of the chorus, including Mark, has degrees or formal training in music. Mark studied music composition at the University of Oregon School of Music.
In 1994 the chorus voted overwhelmingly to unionize and join the American Guild of Musical Artists (a member of the AFL-CIO). Mark was one of the union organizers, and was elected to the Negotiating Committee which concluded its first contract with the Arizona Opera Company in March 1995. The process was not without its own operatic drama, several times spilling over onto the front page of the local papers - particularly during the short-lived strike of the 94/95 season's Rigoletto. In 1997 Mark continued his participation on the Negotiating Committee which successfully concluded a second contract (with no drama) to run three years, and in 2000 helped negotiate a third contract to run four years. The last was conducted using Interest-Based Bargaining. In 1999-2000, Mark served as Vice-Steward (Tucson) and represented the union as a Delegate to the Southern Arizona Central Labor Council.
Mark took a sabbatical year for the 2002/2003 season to focus on the startup of the Dawn mission.