The recent Quantum Hall experiments in graphene have confirmed the theoretically well-understood picture of the quantum Hall (QH) conductance in fermion systems with continuum Dirac spectrum. In this paper we take into account the lattice, and perform an exact diagonalization of the Landau problem on the hexagonal lattice. At very large magnetic fields the Dirac argument fails completely and the Hall conductance, given by the number of edge states present in the gaps of the spectrum, is dominated by lattice effects. As the field is lowered, the experimentally observed situation is recovered through a phenomenon which we call band collapse. As a corollary, for low magnetic field, graphene will exhibit two qualitatively different QHE's: at low filling, the QHE will be dominated by the "relativistic" Dirac spectrum and the Hall conductance will be odd-integer; above a certain filling, the QHE will be dominated by a non-relativistic spectrum, and the Hall conductance will span all integers, even and odd.The quantum Hall effect (QHE) is one of the richest phenomena studied in condensed matter physics. This effect is characterized by certain conductance properties in two-dimensional samples i.e. the vanishing of the longitudinal conductance σ xx ∼ 0 along with the onset of a quantized transverse conductance σ xy = ν e 2 h . Recently several experimental groups have produced twodimensional plane films of graphite, commonly known as graphene sheets 1,2 , which exhibit interesting QHE behavior.Graphene has a theoretical history beginning with the study of the band structure of this planar system in 3 . From these humble beginnings it has gone on to be studied intensely because of its Dirac structure. The bands can be effectively characterized by massless (2+1)d Dirac fermions4 . This continuum model of graphene has been subsequently used to study the (2 + 1)d parity anomaly 5 and as a model system for the relativistic quantum Hall effect (RQHE) 6,7,8 . A quantum spin Hall effect has also been predicted in graphene 9,10 , but the intrinsic spin orbit gap is probably too small to support a measurable phase 11,12 . The latter studies were based on the recent experimental work done on the QHE in graphene by two independent groups 1,2 . These two groups confirm an interesting behavior in graphene in which the transverse conductance is quantized as an integer plus a half-integer σ xy = (n + 1 2 )4e 2 /h, where band and spin degeneracies have been taken into account. Although unrelated to the parity anomaly, this behavior of the Hall conductance was in fact obvious in the seminal work of Jackiw and Rebbi 13 . On the basis of the argument for the RQHE 6,7,8 the experimental groups conclude that this is an interesting new phenomena completely explained by the relativistic Dirac spectrum of graphene. We want to improve on this argument for several reasons. For very large B the lattice is expected to dominate the behavior of the Hall conductance. In this regime the Dirac argument cannot be valid, since, by virtue of being a continu...