Start with Secrets of a Summer Night. It is the first of the four Wallflowers, and the Wallflowers is the series everything else in Kleypas's historical work orbits: four unmarried women at a country house party agree to help each other find husbands, one novel each, and all four keep appearing in each other's books and in the series that follow.
The obvious alternative is Devil in Winter, the third Wallflower and the book most often named her best. Do not start there. Its hero, Sebastian, Lord St. Vincent, spends the previous novel attempting to abduct and forcibly marry one of the four heroines, and the entire force of Devil in Winter comes from having watched him do it. Read cold it is a competent marriage-of-convenience romance. Read in order it is the reason people recommend Kleypas at all.
The Wallflowers
Secrets of a Summer Night, It Happened One Autumn, Devil in Winter, Scandal in Spring. Four seasons, four heroines, strictly in that order.
The Gamblers, and why they come next
Then Came You and Dreaming of You were published a decade earlier, in 1993 and 1994. Dreaming of You is the famous one — Derek Craven, a gambling-club owner out of the London rookeries, and the book a great many long-time romance readers name as their favourite of hers. They are earlier work: shorter, broader, with more of the coercive plotting the 1990s genre ran on. Read Then Came You first, since it introduces the club world, then Dreaming of You. The connection to the Wallflowers is real rather than decorative — the gaming house at the centre of Devil in Winter comes out of these two books.
The Hathaways
Mine Till Midnight (Platinum Romance Series), catalogued with an imprint tag and published simply as Mine Till Midnight, then Seduce Me at Sunrise, Tempt Me at Twilight, Married by Morning.
That is four of five. The final Hathaway novel, Love in the Afternoon, is not in our catalogue, and it is the one that resolves Beatrix's story — so the series as we hold it ends one book early. Buy it separately. The Hathaways also share a world with the Wallflowers: the hero of the first book works at the same gaming club and appears in the earlier series before he gets his own.
The Ravenels
Cold-Hearted Rake, Marrying Winterborne, Devil in Spring, then Devil's Daughter. Two are missing between and after: Hello Stranger sits fourth, and Chasing Cassandra and Devil in Disguise close the series.
This is where reading the Wallflowers first pays off properly. The hero of Devil in Spring is Sebastian's son; the heroine of Devil's Daughter is his daughter; and Sebastian himself walks through both, twenty-five years older and still himself. None of that lands without the earlier books.
What else she writes
Kleypas also writes contemporary romance — the Travis family novels beginning with Sugar Daddy, and the Friday Harbor books. They are not in our catalogue and they are a separate decision; the voice carries over, the period trappings obviously do not.
Two plain notes
These are explicit. Sex scenes are frequent, detailed and central rather than incidental. And "in order" means something particular in romance: every book resolves its own couple completely, so nothing is ever left hanging, but the pleasure is cumulative — the villain of one book is the hero of the next, and the friends are still in the room. The Lisa Kleypas hub has the rest.
Follow the full ordered path here: Lisa Kleypas books in order: where to start with the Wallflowers.