The tribological properties of metals produced by additive manufacturing (AM) techniques are not well understood. Recent literature has produced contradictory findings on the wear and friction performance of AM steel compared to conventionally manufactured steel. Beyond tribology, scientists and engineers observed that AM produces alloys with unconventional microstructures, in turn giving rise to unconventional properties. Furthermore, they observed that the resultant microstructure is a direct function of the AM process parameters. In this thesis, a bottom-up, experimental approach is used to uncover the complex role the AM-induced microstructure plays in the tribological response of steel (first aim of the thesis). Several tribological set-ups (reciprocating sliding, in-situ/ex-situ SEM micro-scratching, macro-scratching) and imaging techniques (SE, BSE, ECCI, EDS, EBSD, white-light interferometry) revealed a great deal of anisotropic tribological behavior (‘tribological anisotropy’) ensues from the microstructure. Dislocation density and arrangement, low-angle grain boundaries, high-angle grain boundaries, crystallographic orientation all contribute to the tribological anisotropy. Based on this knowledge, the AM process parameters were controlled to produce steel tribosurface with spatially defined microstructure design (referred to herein as ‘multigrade tribosurface’). These multigrade tribosurfaces in turn exhibit multigrade tribological properties (second aim of the thesis) not achievable via conventional manufacturing routes. In particular, it was revealed that the Taylor factor (accounting for orientational stiffness of the underlying crystal) correlates with the coefficient of friction during sliding over a wide load range. Furthermore, it was revealed that the presence of strong crystallographic texture, or lack thereof, correlates with the susceptibility to generating wear debris. The results in this thesis, by and large, explain the tribological nuances of AM alloys and demonstrate the AM technology’s potential to furthering the field of tribology.