A postdoc asks—
Do I really have to write a cover letter? Most of the applications I’m looking at make it optional. What’s the point in just writing out my resume in paragraphs?

While it's true that someone could potentially get hired without writing a cover letter, cover letters are a good idea in cases when you are applying for a job title you have not had before (the case for most people at UCSF!). But it’s not just a box to check, it matters what you write—a good cover letter will actively strengthen your application, while a bad one can actually work against you. 

Speaking of bad ones, I agree—a cover letter generated from your resume is pretty pointless! Writing your resume out in prose form doesn’t add any helpful information and is effectively a waste of your time and theirs. 

A good cover letter has different information in it: explains why you want to do the job (not that you are able to do the job), what you plan to be doing in the future (since the resume can only address the past), and addresses any specific concerns that arise from your resume. An even better cover letter will also demonstrate skills that can’t be described convincingly in a resume (i.e. communication skills), and contextualize key accomplishments with background and details that don’t fit in a resume. 

It’s worth noting also that while a cover letter may be listed as optional by the application system, many hiring managers actually do expect them and won't seriously consider an application that doesn’t have one. To know if that’s the case, you’d have to do an awful lot of digging—time you could spend writing a cover letter! 

-Ray Care, Program Director, Career Development Team for Researchers