As a dealer, historian, advisor, writer, and expert, Butterfield has worked with many of the most distinguished private collectors and institutions in the world, including:

Musée du Louvre 
The Metropolitan Museum of Art 
National Gallery of Art 
Kimbell Art Museum 
National Gallery of Canada 
Philadelphia Museum of Art 
High Museum of Art 
The Frick Collection 

The National Gallery, London 
National Galleries of Scotland 
Los Angeles County Museum of Art

Seattle Art Museum 
The Art Institute of Chicago 
Phoenix Art Museum 
Detroit Institute of Arts 
Allen Memorial Art Museum 
Art Gallery of Ontario 
Eugene Victor Thaw Art Foundation 
The Andrew W. Mellon Foundation 
Lloyds of London 
And many private individuals