We have observed Ha rotation curves of ten dwarf and five LSB galaxies, and derived the density profiles of their dark halos both from direct inversion of the rotation curve and from parametric fitting of galaxian mass components. Describing the inner density profile as rho proportional to r(-alpha), the inversion of the rotation curve yields slopes in the range 0 <= alpha <= 1 for the sample; fitting mass models yields slopes which are unconstrained in the range 0 <= alpha <= 1 for each individual galaxy. We discuss and model the main observational errors that we can expect to be acting on the data, and derive a probability distribution of expected observed inner halo slopes. We find that halos with alpha = 1 may explain the observed a distribution if the errors have the right model amplitude. Halos with alpha = 0 appear to be inconsistent. with the data.
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