This paper is devoted to the open problem in F 1 -geometry of developing K-theory for F 1 -schemes. We provide all necessary facts from the theory of monoid actions on pointed sets and we introduce sheaves for M 0 -schemes and F 1 -schemes in the sense of Connes and Consani. A wide range of results hopefully lies the background for further developments of the algebraic geometry over F 1 . Special attention is paid to two aspects particular to F 1 -geometry, namely, normal morphisms and locally projective sheaves, which occur when we adopt Quillen's Q-construction to a definition of G-theory and K-theory for F 1 -schemes. A comparison with Waldhausen's S • -construction yields the ring structure of K-theory. In particular, we generalize Deitmar's K-theory of monoids and show that K * (Spec F 1 ) realizes the stable homotopy of the spheres as a ring spectrum.