I review efforts to determine the form and any lower limit to the initial mass functionin the Galactic disk, using observations of low-mass stars and brown dwarfs in the field,young clusters and star forming regions. I focus on the methodologies that have been usedand the uncertainties that exist due to observational limitations and to systematicuncertainties in calibrations and theoretical models. I conclude that whilst it ispossible that the low-mass IMFs deduced from the field and most young clusters aresimilar, there are too many problems to be sure; there are examples of low-mass clusterIMFs that appear to be very discrepant and the IMFs for brown dwarfs in the field andyoung clusters have yet to be reconciled convincingly.