Abstract: A nib retaining assembly for a writing instrument to hold a capillary writing element or nib of small cross-sectional dimension in position against writing pressure, the nib retaining assembly including a nib receiving main longitudinal passageway formed by offset portions through which the capillary element extends. The capillary element is held by light staking within an axial bore of a nib holder which, in turn, is inserted into a seat at one end of the passageway. Because of the passageway offset portions and an intermediate camming surface, a capillary element inserted into the passageway is deflected around an internal shoulder so as to be forced into frictional engagement with the passageway walls to hold the small nib in writing position without disturbing the capillary action. In one embodiment of the invention, the passageway is defined by a nib retaining adapter inserted into a seat in the barrel; while in another embodiment the passageway is defined by the tubular barrel of the instrument.