Patti LuPone's evening of song, ''Matters of the Heart,'' is being performed in the lofty grandeur of the Vivian Beaumont Theater at Lincoln Center, but it creates the sedate atmosphere of a salon. The lush green backdrop curtain, the elegant flower bowl perched on the piano, Ms. LuPone's de la Renta gowns and her formally attired accompanists -- a pianist, Dick Gallagher, who is also the arranger and musical director, and a string quartet -- all contribute to an intimate formality that the music never disturbs and never tries to.
The program, taken largely from Ms. LuPone's CD of the same title that was released last year, is devoted to the theme of love and its corollaries. The songs, from writers like Rodgers and Hammerstein and Stephen Sondheim, Randy Newman and Joni Mitchell, are a pleasant mixture of classics, show tunes and pop songs bespeaking full or empty hearts, spiced occasionally by a mischievous twitch of the loins.
''I think everyone in the theater has been in love,'' Ms. LuPone says in her introductory patter, which gives you an idea of the sweetly unchallenging nature of the show, which opened yesterday and will be presented Sundays and Mondays through Dec. 17.
Ms. LuPone has generous and varied gifts as a singer. Her voice has the capability of bringing down a Broadway house, but she is largely in delicate mode here, the brass of her persona evident mostly when she sings about the wicked impulses of lust or the sly manipulations of courtship.
She brings a nice touch of the bawdy to a suggestive lyric, as in Mr. Sondheim's ''I Never Do Anything Twice.'' And her experience as a stage actress, both dramatic and comic, enlivens a handful of conversational songs. ''Playbill,'' by John Bucchino, about two strangers meeting at a bar after a show and, they hope, entering a courtship, is delicate, tense and touching. On the other hand, Ms. LuPone delivers Dillie Keane's ''Shattered Illusions,'' a jaunty comic confessional about what one expects from a lover and then what one gets, with an understated vaudevillian charm.
One reason these stand out is that most of Ms. Lupone's selections here have sincerity at the center, a spirit that is unabashedly underscored by Mr. Gallagher's saccharine arrangements. As a singer, Ms. LuPone is not necessarily averse to the overly somber meaningfulness of bubble-gum pop; she does have a whiff of the self-important diva in her. In songs like Gilbert O'Sullivan's ''Alone Again (Naturally)'' and ''Air That I Breathe'' by Albert Hammond and Michael Hazelwood, the treacle factor gets a little wearing, and the show as a whole evokes an uncomplicated and rather polite sentimentality.
This isn't necessarily a bad thing, and, particularly as the holidays loom, to quibble over too much sentiment is a bit unseemly. In the end, ''Matters of the Heart'' is not a show for Scrooge, and though it isn't a holiday show, it exudes the melancholy hopefulness of New York at Christmas, the sense of walking through Rockefeller Center alone at dusk in the freezing cold.
When Ms. LuPone closes the evening with ''Hello, Young Lovers'' and ''My Best to You,'' it makes you want to hold someone's hand.