All of Caroline's books can be read alone, but if there's a strong overarching plot to the series, you'll enjoy them more if you read in series order.
​Sometimes, however, secondary characters from one series go on to get a book in another series. This is the suggested reading order if you're the type of person who gets twitchy about not reading those secondary characters in order.

​Victorian RomComs

The Lass Who Lost a Shoe*
The Lass Who Kissed a Frog
The Lass Who Loved a Beast
The Scholar and the Scot
The Doxy and the Duke
The Duke's Virgin Sister
The Earl's Brazen Widow
The Rake's Insatiable Bride
The Sinner's Tempting Captor
​The Polka-Dotted Bathing Costume (novellette)
The Duke's Deceitful Governess 
...and then the rest of the Surprise! Dukes 

*The hero in this book appears as a secondary character throughout the Everland Ever After books, but since those are a different genre (historical western) and a different heat level (no spice), AND a different comedy level (really, Caroline, why did you even bother linking them?), it's not really necessary to read any further back.

Medieval Scottish RomComs

A Scot Mess
Scot on Her Trail
Getting Scot and Bothered
In Scot Water
Drop It Like It's Scot
Scot to the Touch
Scot Under the Mistletoe (novella)
Too Scot to Hold
Reindeer Romance (novellette)
Plaid to the Bone
Not Half Plaid
Ye Give Love a Plaid Name
Don't Give a Damn About My Plaid Reputation
Plaid Case of Loving Ye
He Kens if Ye've Been Plaid or Good (novella)
Plaid Attitude

Medieval Scottish Adventures

The Sinclair Hound
The Mackenzie Regent
The Sutherland Devil
The MacLeod Pirate
The Laird's Yulebringer (novellette)
The Bruce's Angel (novella)
The Highlander's Angel
​The Laird's Angel
The Thief's Angel
The Pirate's Angel