Like all other types of students, your journey to find adult grants starts with filling out the Free Application for Federal Student Aid (FAFSA). This is particularly important if you are in a low income situation. While the government doesn't have a specific set of adult grants, they do have the Federal Pell Grant which is their largest educational aid program. Since it is a need based program, however, you must show that you are qualified to apply for it on the FAFSA. Even if you feel like you make too much money for the grant, still send in the packet. You may qualify for student loans which can still help.
Your best bet is to look in the nonprofit and private sectors for adult grants. There are a hundreds of foundations and associations that will give you money to go back to school. If you are a woman or belong to a minority group, start with programs that offer adult grants for your particular demographic. For example, the National Black Nurses Association gives money to African-Americans enrolled in nursing programs. Women getting back into the workforce or trying to advance their career are eligible for adult grants from the Business and Professional Women Foundation.
Other places you can find adult grants include corporations as well as individual universities. Many corporations offer adult grants to students pursuing degrees. In addition to that, some employers encourage their workers to continue their education and will pay for a certain amount of credits if you can prove the classes fit in with your job description. Contact the HR department in your company to find out if your employer offers this type of program. The school you are enrolled in may have a grant program. The financial aid office can provide you the information on it if they do. Going back to school doesn't have to be expensive. Just use all of the tools at your disposal to find the best adult grants available.