The answer provided in this question does not work with classicthesis: Double line spacing
Specifically, using setspace and \doublespacing does not work. Using \linespread does but this introduces spacing in e.g. figure captions and tables too, which is not optimal.
Classicthesis can be found here: http://www.ctan.org/pkg/classicthesis
Since Classicthesis is used a lot for PhD theses, and a lot of these are required to be double spaced, I'm probably not the only one who's had this problem. Somebody had previously asked this question and it was (erroneously?) marked as a duplicate, linking back to the question above.
I'm not sure if I need to edit something in classicthesis.sty itself?
classicthesiswas designed for nice looking documents, even tought the implementations is a bit rough, the effort should be appreciated. Doublespacing and classicthesis should should contradict by common sense. – Johannes_B Oct 04 '14 at 14:34\documentclass{report} \usepackage{classicthesis} \usepackage{setspace} \usepackage{blindtext} \begin{document} \doublespacing \chapter{matthew doublespace} \blindtext[4] \end{document}– Johannes_B Oct 04 '14 at 14:36\doublespacingand had it before the\begin{document}instead of after it, which I realised after reading your example. It now works. I am completely agreed about not normally changing the very nicely designed defaults, but sadly double spacing is a requirement from my university that I have no say in. – Matthew Oct 04 '14 at 15:36