The problem (as KennyTM noted) is that LaTeX won’t hyphenate words with dashes in them. Luckily, there’s a standard package (part of ncctools) that addresses that very problem, called extdash. This defines new hyphen and dash commands that do not disrupt hyphenation, and which can allow or prevent line breaks at the hyphen/dash. I prefer to use it with the shortcuts option, so I can use, e.g., \-/ rather than \Hyphdash. Here’s what you want:
\usepackage[shortcuts]{extdash}
…
multi\-/disciplinary
To prevent breaking at that hyphen, use multi\=/disciplinary
(Aside: The Chicago Manual of Style advises dropping the hyphens attaching affixes like ‘multi’, unless the word is ambiguous or unintelligible without it.)