Grad school letter of recommendation dilemma - advise me!

As one or two of the more bored among you all may remember, I’m in the process of applying to grad schools - specifically, PhD programs in molecular biology. I have two of my three letters set, but I’m trying to decide what to do about the third. I have two options:

The first would be to have my immediate supervisor write one (I work in a clinical molecular lab). She knows me very well - better than anyone else I’ve worked with - and would write me a very glowing and enthusiastic letter. However, she only has a Medical Technologist degree - the equivalent of a bachelor’s.

The other option would be to ask one of my medical directors. She’s a highly respected PhD that has done a lot of good work in her field, and I think she’s fairly well known in the community. However, she doesn’t know me as well. I’ve worked in her lab for years, but the amount of personal interaction has been limited. I think she thinks well of me, but she wouldn’t be able to include the kind of personal knowledge my supervisor has.

So what’s more important to the people reading these, personal knowledge or the credentials of the person writing? What would you do?

What are the other two letter like?

IMHO, it depends in part on what you’re trying to accomplish with the letter. Who wrote your other two? What is the greatest weakness in your application? What is the general strategy of your application? For nine out of ten applicants, the more personal letter will be better. Personal knowledge is the whole point of a letter of recommendation. But it’s possible, while unlikely, that you have some weakness in your application that could be remedied by a more prestigious recommender.

I was able to submit 4 letters, and one of my recommenders encouraged me to do so. Don’t know how it works in your field, but thought I’d mention it.

As someone who has sat on both graduate admissions committees and academic hiring committees, I am much more swayed by a detailed and glowing letter from someone who knows the applicant well than I am by a more general letter by someone who is well-known.

Option Three: Do both.

I’ve found that prestigious often equals spread six ways to Sunday. On at least one occasion, I was told by a more senior person to have one of her underlings write the letter, and she would add to it/sign off on it. Would this work?

I’m not sure of the politics of something like this, since you don’t want to offend anyone involved. You might be able to plant the suggestion: “Head researcher - I know you are very busy, but I am in the process of applying to grad school, blah blah blah, if you’d like maybe someone else could write the body of the letter to make things easier, since I don’t want to take up a lot of time? etc. etc.”

I dunno…it could work, but might be delicate to do. Of course, this is coming from the person whose unofficial (and very senior) advisor has apparently been trying to contact her for days, unsuccessfully… ::head into desk::

Good luck with the mol. bio! I’m not my nook of science, but I always did like it.

Thanks for the opinions - they helped. The other letters I have are both from other medical directors at our lab. They’re good, I’m sure, and from fairly well-known and respected people. The more I think about it, the more I think it’d be smarter to go with my supervisor. So that’s what I’m doing. Thanks again!

IMHO, I would not mention that you name is smeghead on the application

Damn. No wonder I never get accepted anywhere!