I didn't get to the interview, but the written test and proofreading exercise took up a week of my time, during which I was trying to find interesting arguments to put forward and to really understand the clinical trial in depth. But they were more focussed on particulars of the grammar rather than content - despite me proofreading everything 5 times, having a friend check over my writing, and running it through Grammarly, I was rejected on the basis of typos/punctuation errors (which were never actually provided), American-British spelling, and on the low score on proofreading exercise (which was done in Adobe Acrobat and timed, and editing in Adobe is cumbersome). I think it is a real shame to prioritise commas over content, especially when in this day and age pedantic things like this are automatically picked up by text editors anyway. In your prep, really focus on grammar the most, otherwise you won't get to the interview stage.
Interview questions [1]
Question 1
What are the key primary and key secondary objectives of this clinical trial?
I passed CV screening and went about the first round (proofreading + writing assessment). They gave me a week for that; the writing assessment involved answering some questions based on a research article, and the proofreading assessment involved making 50+ edits to an article and writing a 300 word summary of an article in 1 hour.
The recruiter + some others review it, and I was then invited to the final stage interview in Boston. It was further away, so I did it virtually -- 15 min presentation w/ questions to an analyst + senior analyst, you present on a report with a similar topic to the writing assessment, and 45 min behavioral interview with a more senior leader. Interview ran long (they ask a lot of presentation followups) and I ended 25 minutes past the timeframe haha, but all good I hope. Interviewers were all sweet and gave gentle feedback/broadened some of your responses in the moment, if needed. It was a bit tough, but make sure to prepare well, and you got this! Still waiting to hear back and will update the result later.
Interview questions [1]
Question 1
Tell me about yourself/why this role? Why Costello specifically?
What would you do if a client told you that you made a mistake in your work?
What kind of culture are you looking for in your workplace?
A time you managed multiple deadlines?
Your background in science and/or writing?
Make sure to ask your interviewers some good questions!
I applied through an employee referral. I interviewed at Costello Medical (London, England) in Feb 2026
Interview
1st stage: submitting CV
if you pass the CV screen: Timed proofreading test and an assessment on a paper on drug discovery
The timed proofreading test was very challenging and required attention to detail and staying cool underpressure.
I applied through an employee referral. I interviewed at Costello Medical in Nov 2025
Interview
Starts with CV and Cover letter. Then a scientific writing and timed proofreading assessment. Finally, a presentation and Behavioural + Technical interview, followed by an interview with the Head of Department.
Interview questions [1]
Question 1
Why Costello? Why are you a good candidate? How would you handle conflicting feedback? How do you deal with mistakes? Do you have experience with scientific communication?