Officially, the concert program at St. Mark’s Episcopal Cathedral kicked off last month with a free organ recital. But the first major program (which also charges an admission) is Sunday afternoon, when peripatetic soprano Maria Jette — who seems to be performing everywhere — appears in a concert of music by Haydn and Mendelssohn.

St. Mark’s has a worthy music series that brings in chamber groups and organists, plus performances by the church’s own Cathedral Choral Society. Next month, for example, the choristers, under the direction of Raymond Johnston, will perform Schubert’s Mass in G, plus shorter works by Handel. And next March, they’ll mark J.S. Bach’s 315th birthday by performing the Magnificat in D.

Sunday’s concert also features the Schubert Trio performing Haydn’s Trio in E-flat Major and Mendelssohn’s Trio in C minor. Members of the trio are pianist Daniel Rieppel, violinist Helen Chang and cellist Thomas Rosenberg.

Jette will perform some of the arrangements of Welsh folk songs that Haydn produced during one of his visits to England in the 1790s. Yeah, even Haydn could be folksy.

St. Mark's Music Series: The Schubert Trio and Maria Jette. Sunday, Oct. 18, 5 p.m. Tickets are $15 for adults and $10 for students and seniors. Admission is free for kids 12 and younger. Tickets can be purchased at the door or at the cathedral’s bookshop.