I'm a junior physics major at a school in the US and I've recently come to the conclusion that I think that I like math better than I like physics. I'm thinking I might like to do mathematical physics in grad school, but since I've spent the last 3 years thinking I'd go to grad school for "normal" physics I'm suddenly very lost and confused. First: I'm mostly confused about which department one interested in mathematical physics should apply to. Most mathematical physicists seem to reside in math departments, but there are still some in physics departments. Should I apply to both? Second: GREs. Should I take both the math and physics GRE? Should I only take whichever one corresponds to the departments I'm applying to? I suspect that I'd do better on the math GRE than the physics GRE - perhaps even significantly so, so maybe it would be to my benefit to not take the physics GRE? Third: Coursework. I'm currently just majoring in physics. If I decided to go this route I'd add on a second major in math, but I'd end up with the bare minimum coursework to graduate (1 semester of algebra, 2 semesters of analysis, 1 semester of complex analysis, 1 semester of numerical analysis, 1 semester of prob/stat, 1 semester of combinatorics, and then 5 other upper division classes of my choice). Would this be enough to get into a competitive grad school? Finally, what do mathematics grad schools look for, and does it change if you want to do mathematical physics? For physics I know that the most important things are research, recommendations, grades, GREs. Mathematical research ability seems more difficult to gauge to me - do they care more about recommendations, for example? What about Putnam scores? Do they factor in? Research? Finally, how do I know if I am even cut out for this? I'm pretty certain that I can handle the math - I've gotten all A's in my math classes (though I have only taken a few upper division) hardly lifting a finger. But I am not the best at physics. I especially found statistical mechanics to be extremely challenging and frustrating and ended up with a B in it despite pouring ungodly amounts of time into it (and still don't feel that I know it very well). I feel like all of the mathematical physicists I've met are godlike at both!