A new paper, “Beyond Teachers: Estimating Individual Guidance Counselors’ Effects
on Educational Attainment” by Christine Mulhern observes significant contributions from guidance counselors to student outcomes:

It’s the last bit that rings truest to me: that counselors are most salient to low-achieving and low-income students because they lack other resources, specifically information. As I’ve noted before, information deserts are real, particularly for potential first generation college students. As modern applied economists, we are obsessed with identification and causality, but don’t sleep on distribution of impacts observed. Her finding that “counselors vary substantially in their effectiveness” is worth consideration and further exploration. Where does that variation come from? The excellence of the best counselors or the negative impact of the very worst? I’ve only a handful of experiences interacting with counselors, but my expectation is that it is both. Given that counselors tend to be woefully paid, I expect that they frequently sort across schools on non-pecuniaries i.e. how pleasant it is to work somewhere, which seems like yet another channel through public school students in affluent neighborhoods will find themselve advantaged.
But that’s enough speculative extrapolating for one day. Read the paper.