Should I invest in my 401k now or pay off my student loans now?

I'm 24 and have been working for about a year and a half. I have about $1k in my 401k and $23k in student loans. I recently upped my 401k contributions to 15% and have been making large payments towards my loans to pay them off asap. With the economy as it is now, should I pay more towards my loans (3.50%-5% interest) or get more in my 401k now while the funds are cheap?

Pay off your debt now, but only if you're serious about doing it. I don't know how much you have to pay off, but if you're going to forgo investments to your 401k, try to pay off the debt within the next year (or sooner if you can) so that you can resume investing into your 401k as soon as possible. You'd be surprised how much even $1,000 can be worth at retirement if you invest it in your 20's.

If your employer matches (very rare these days), you should deduct the same amount – say they match 6%, you put in 6%.
If your employer doesn't match, you shouldn't put in any more than 8% and use the rest to pay more on your loans. Yes, the funds are cheap, but this may not be a market bottom, so don't worry about that.
Imagine if you lost your job in 6 months – you would be better off if your balance on your loans was less. Best bet is to find the optimum balance to save and get out of debt.

You can do both. Most importantly pay as much as you can into your 401k. It will grow by leaps and bounds and you can borrow against it later when you get ready to buy your first home. You can pay your student loans off faster also by adding 1/12th of a payment to each payment. Chances are your student loan interest rate is lower than what you would make in your 401k. Stash your cash in the 401k – especially if your company matches! That's free money, usually up to 4% of your salary.

Add to your 401k.

Student loans are usually the lowest interest loans around. If you have other types of debt: credit cards, cars…ect. I would pick away at that first. Student loans are usually a low priority type of loan because of the way they're set up.

get those student loans paid off. the 401k can wait.