Third Person (Limited Omniscient)
In all his books, James's preferred narrative voice is the Third Person Limited Omniscient, and The Wings of the Dove is no exception. In The Wings of the Dove, however, he jumps from one character's mind to another by separating the story into different books.
For example, Book One of Volume One opens with "She waited, Kate Croy, for her father to come in." (18.104.22.168). From this point onward, you have access to Kate's thoughts but no one else's, as you see in lines like, "When her father at last appeared she became, as usual, instantly aware of the futility of any effort to hold him to anything." (22.214.171.124). The gap in knowledge between what we know about Kate and what we know about her father shows us that the narrator is going to limit us to what's going on in Kate's head.
James does this same thing throughout the rest of the book, giving us insight (at different points), into the minds of Merton Densher, Susan Stringham, and Milly Theale. By hopping around like this, James gives us a VIP tour of how people's differing perspectives can make communication extremely difficult—if not impossible—when emotions run high and people start to speculate on what others are thinking.