One option that many teen homeschoolers and unschoolers use is their local Community Colleges. But this option can be available to any teen! Local Community Colleges offer a wide variety of courses, often more interesting to teens- since they can tailor their course load to their interests. Community Colleges tend to be free from the teenage drama and bullying that can be pervasive in high schools, as well.
In California, anyone can attend Community College if they are (1) 18 or above, OR (2) have a high school diploma, OR (3) have passed the CHSPE. (Teens need to be at least in 2nd semester of 10th grade or 16 years old to take this). I believe that most states have these same requirements- but you may want to check with your local Community College to make sure.
High school students can also take Community College courses through concurrent enrollment, as homeschool or regular high school school students, but these kids may have lower priority getting the classes they want and be limited in the number of units they can take. Every community college has different requirements. To find out, look up “concurrent enrollment” on your local Community College’s website.
So what if you have a 14 to 17 year old who is bored to death in high school? or for whom school is not working for any reason? or who is already homeschooling, but wants greater access to community college courses? Well, potentially you can enroll them in your own homeschool, by filing a private school affidavit, and then simply graduate them. (The link links you to California’s affidavit web site- you will need to search your own state’s requirements here.) Pam Sorooshian has a nice diploma template on her Learning Happens Blog. (An unschooling family’s blog you may want to check out anyways– her grown children are doing wonderfully without schooled childhoods.)
Another option is going through a program such as Pacific Sands Academy– where your teen creates an online portfolio of his/her passions and interests, and earns a high school diploma this way. This program is open to teens in any state, and has worked with teens in the US, Canada and Mexico. This diploma will come with a narrative transcript discussing your teens strengths and achievements- which can also be used as a recommendation.
Either way, this kind of diploma will not be accredited, but in the scheme of things accreditation really doesn’t matter, as I discuss in this blog post. A high school diploma will still count as a high school diploma in most situations.
So consider this: your teen can graduate from high school when s/he is ready (at any age), and begin taking community college courses in earnest. S/he can take 2, 3, 4, 6, or more years to complete an Associates Degree, and as part of that quest, work towards completing the transfer requirements for the University of his/her choice.
I believe in interest-led, self-directed learning. I love helping teens find lives of passion and fulfillment outside of traditional academia.
Learn Your Way 
[…] a high school diploma. I discuss how to approach community college “underage” in this post. However, the other option is to attend community college concurrently enrolled in a high school […]