Being in the ARNG will not necessarily prepare him to be or make him a better officer, it will make him a better private. If he is assigned to a good unit, then there could be some value as an SMP cadet, if they give him lieutenant responsibilities. However, he will not be an SMP cadet until he contracts with ROTC. Until then, he will be a private and expected to go to basic training and AIT. He will also be subject to any mobilizations, as he is not protected as an SMP cadet until he contracts with ROTC. He could avoid going to basic and AIT, if he enlists as 09R (potential SMP cadet), but they tend to want you to be able to contract with ROTC within the year. There are pros to enlisting to the ARNG, as it is a source of part time income, gives some military experience, and can provide financial assistance through the GI Bill, Tuition Assistance, and Student Loan Repayment, but that requires attending BCT/AIT and fulfilling a service obligation. The biggest thing is to identify why your son wants to join the ARNG. Will it fulfill an actual need? I am actually pro-SMP for state school attendees as many states will cover the cost of the tuition if you are in there ARNG, and it is a big help for cadets who can't afford college and are not scholarship eligible. I was an SMP cadet myself for financial assistance prior to commissioning onto active duty.