I would like to visit the US for 5 days before making a trip to Guatemala for 1 month. After my time in Guatemala I would then like to return to the US for 1 month to visit family before returning to work and family in my home country. Is this allowed?
There's no law or regulation prohibiting this. Each time you enter, however, you have to convince the border officer that you are a genuine visitor. Two visits with a combined duration of about five weeks isn't likely to come close to being problematic in this regard unless you are stretching yourself financially.
As mentioned in another answer, you need to have a reason to travel in this frequency. I have been in US in begin of January for a business travel and I traveled again in the end of January as vacation. So, I traveled again to US 2 weeks after and I did not have any problem.