on Just Publishing Advice:
Do you capitalize long prepositions when you prepare your book title for publishing?
The general rules for capitalization in book titles are quite straightforward. However, when it comes to prepositions, you should take care.
Short prepositions and conjunctions are generally not capitalized unless it is the first word in a title.
But when it comes to long prepositions such as underneath, throughout, and without, you have a choice.