In my MWE below, I sort my bibliography with the nyt option (name-year-title), cf. the biblatex manual under 3.1.2.1 General. Then I also include sortcites = true, which according to the manual will "sort citations if multiple entry keys are passed to a citation command. If this option is enabled, citations are sorted according to the global sorting order of the bibliography."
Since the "global sorting order of the bibliography" in my case is name-year-title, I'd expect my citations to be sorted first by name, then by year, and finally by title. But as the MWE below demonstrates, my citations are simply printed in the order given in the cite command. I was expecting "Lennon" to appear before "McCartney" since l preceeds m, but this does not happen. I am either not understanding what sortcites is supposed to do, or I am setting the options incorrectly. What do I need to do to automatically sort my citations by name?
\documentclass{article}
\usepackage[style = authoryear-comp, sorting = nyt, sortcites = true]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@book{mccartney1965,
author = "Paul McCartney",
title = "Yesterday",
year = "1965"}
@book{lennon1967,
author = "John Lennon",
title = "Lucy in the sky with diamonds",
year = "1967"}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\cites{mccartney1965}{lennon1967}
\printbibliography
\end{document}

\citesmulticite commands are not designed to sort their arguments, but Audrey has found a way to make them do it anyway Sorting citations using \cites command in biblatex. BTW: Didn't you ask this before? – moewe Feb 17 '15 at 15:23sortcitesis simply an vacant command? – Sverre Feb 17 '15 at 15:25sortcitesis not vacant, you can use\cite{mccartney1965,lennon1967}where the citations are then sorted accordingly, but you will lose the possibility to specify a post/pre-note for each citation separately. For\citescommands thoughsortcitesdoes nothing. – moewe Feb 17 '15 at 15:26latexmk, and it does runbiber. I haven't changed my option at all - I setsorting = nyt, sortcites = truefrom the start. – Sverre Feb 17 '15 at 15:28\citesdoes not supportsortcites. – moewe Feb 17 '15 at 15:32INFO - Sorting list 'nyt' of type 'entry' with scheme 'nyt' and locale 'en-US'. But still McCartney before Lennon. – Sverre Feb 17 '15 at 15:34.bbldoes indeed put Lennon before McCartney. Does this mean thatlatexmkis not runningbiberenough times or something? – Sverre Feb 17 '15 at 15:40.bblfile should be the same as the order in the bibliography. Since\citescannot sort its arguments, though, that is irrelevant. – moewe Feb 17 '15 at 15:43bibermanually. Sincemoewealso gets that, it seems to be a mystery why you get something else. But as @mowew points out, I have indeed asked this question before (I couldn't find it by searching), so I'm voting to close my question as a duplicate. – Sverre Feb 17 '15 at 15:51\cites{mccartney1965,lennon1967}... – Paul Gaborit Feb 17 '15 at 16:35prenoteorpostnoteis required, this workaround can't work... You may add this remark to your question. – Paul Gaborit Feb 17 '15 at 16:45