Julian Wachner leads the The Washington Chorus as it celebrates two notable milestones: Gustav Mahler's 150th birth year in 2010 and his 100-year death in 2011. Outstanding soloists join the chorus in its 50th anniversary gala concert to pay tribute to the German composer. Saturday, May 1, at 1 p.m. Kennedy Center Concert Hall. Tickets are $15 to $65. Call 202-467-4600 or visit kennedy-center.org.