How do we use the Other to make sense of who we are? A common assumption is that people positively affirm social identities by excluding an inferior Other. This article challenges that restricted notion by focusing on the variation and situational fluidity of alterity construction (othering) in identification work. Based on an ethnographic study of a change project in a public hospital, we examine how nurses, surgeons, medical secretaries, and external management consultants constructed Others/otherness. Depending on micro-situations, different actors reciprocally differentiated one another horizontally and/or vertically, and some also appropriated otherness in certain situations by either crossing boundaries or by collapsing them. The article contributes to theorizing on identification work and its consequences by offering a conceptualization of the variety of othering in everyday interaction. It further highlights relational agency in the co-construction of social identities/alterities. Through reciprocal othering, ‘self’ and ‘other’ mutually construct one another in interaction, enabled and constrained by structural contexts while simultaneously taking part in constituting them. As such, othering plays a key role in organizing processes that involve encounters and negotiations between different work- and occupational groups.