Factors contributing towards falls in older age during overground walking have been widely studied. Stepping behaviour, balance and head posture control during stair negotiation in young adults (YA) and older adults with either lower (LROA) or higher (HROA) risk of falling during midstair negotiation have not been investigated. The aims of the thesis were threefold. Firstly, age-related changes in gaze behaviour were investigated. The main finding was that older adults fixate stair edges for longer than YA. Secondly, the effect of manipulating visual information on stepping parameters and balance control was compared between YA, LROA and HROA. For stair ascent, stepping and balance control was preserved in LROA and HROA and highlighted stair edges led to increased foot clearance in all groups. For stair descent, HROA demonstrated smaller foot clearance than LROA and highlighted stair edges improved balance in LROA and HROA. Thirdly, head posture was studied in YA, LROA and HROA. Compared to walking, LROA and HROA demonstrated more variable head posture than YA. Overall the findings suggest that adults use visual and probably proprioceptive information about stair edge locations to negotiate stairs and HROA benefited from highlighted stair edges. HROA should be included in future stair negotiation studies.