Non-STEM Letter of Rec for STEM PhD Programs I am applying to PhD programs in math, cs, and statistics this fall at roughly top 15 US schools. I will be having recommendations from two professors who I worked on projects with personally and who I believe can speak strongly to my research abilities; they are the only two PIs I’ve had. For my third letter, I am thinking about asking a history professor I’ve had in &lt;15 person classes for three semesters. I think he can speak well to my work ethic and communications skills. I also can likely get a letter from a professor I had in a microcontroller lab class which I did well in, had a friendly relationship with her, and completed a month-long design project, but this was few years back and the course was introductory. I think my history professor can write the stronger and more personal letter, but would the types of programs I’m applying to prefer the STEM professor’s letter? What about including the history professors’s as a supplement?
It's important that you show potential for research in your application including letters of recommendation.
For me, I had three letters, two from people I did research with as an undergraduate, and one from a history of science professor I had taken a couple courses with (definitely a more &quot;history&quot; slant than &quot;science&quot;).
That worked for me. No idea whether it will work for you because ultimately it will depend on who reads your letters, what they say, and what the rest of your application says.
Remember rule #1, and then go from there:
It's important that you show potential for research in your application including letters of recommendation.