What color do orange and green make?
Orange and Green make olive.

Orange and Green make olive, #969612. That is the result in equal parts, mixing pigment rather than light - paint, ink and dye all behave this way.
Equal parts orange and green · #969612
Change the ratio
Very little of a mix is ever half and half. Shifting the balance moves the result along the range between the two colours.
3 parts orange, 1 part green · #d08c07
Equal parts · #969612
1 part orange, 3 parts green · #50a021
Lighter and darker
With white added - a tint · #cbcb89
With black added - a shade · #5a5a0b
Why it works
Pigment mixes subtractively: orange paint absorbs the wavelengths it is not reflecting, green absorbs its own set, and olive is what neither of them absorbed. This is why paint behaves differently from a screen, where light adds together instead.
Frequently asked questions
What color do orange and green make?
Orange and Green make olive, #969612. Mixed in equal parts that is the result you get with paint, ink or any other pigment.
How do I make the result lighter or darker?
Add white for a tint - here that gives tan. Add black for a shade, which gives brown. Add white a little at a time, because it takes far less than people expect to shift a mix.
What happens if I use more orange than green?
Three parts orange to one part green gives orange. Reversing it to one part orange and three parts green gives olive instead.
Does this work the same way on a screen?
No. Screens mix light additively, so red and green light make yellow there. These results are subtractive - paint, ink, dye and pigment - which is what people mean when they ask what two colours make.