One challenge for workplace leadership in the twenty-first century is that leaders need to properly organize workplace experiences for employees (Graen and Canedo, 2017). A large part of employees’ work experiences hinge on the quality of the leader-follower role relationships, on which leaders have a major impact. Indeed, leadership is a relational phenomenon and leader-follower role relationships are crucial for leadership effectiveness (Gottfredson and Aguinis, 2017; Uhl-Bien, 2006). Two such relationships have been extensively studied in leadership research. One is leader-member exchange (LMX), which captures the quality of the reciprocal role relationship through which valuable resources are exchanged between a leader and a follower (Liden et al., 1997). The other is leader identification (LID, hereafter), which reflects the extent to which a follower’s beliefs about the leader are self-defining (Kark et al., 2003); that is, his/her perceived oneness with the leader (Ashforth et al., 2016). Although separate lines of research establish LMX and LID as important mediators of leadership effects (e.g. Dulebohn et al., 2012; Zhu et al., 2012), they merely coexist in the leader-follower role context. How they work together to mediate leadership effects remains unclear (cf. van Knippenberg et al., 2004). As Bono and McNamara (2011, p. 659) noted, most mediators in leadership research, “even when they are conceptually related to each other, are studied in isolation. Typically, each is treated as if it is the unique process […] and other known mediators are not considered.” Thus, this research purports to explicate how LMX and LID concurrently function as mediators for leadership. Research suggests that LMX provides a social exchange mechanism and LID offers a self-concept explanation of leadership (Dinh et al., 2014). As a further distinction, some scholars argue that LMX is a “somewhat calculative and instrumental process,” while also acknowledging that these role relationships also include “communal and less calculative aspects,” such as identity-based attachment in the subordinate-manager relationship (Sluss and Ashforth, 2008, p. 808). However, others consider LMX and LID as subsumed in a leader-focused social exchange process (Lavelle et al., 2007). Although the preceding views are not necessarily conflicting, we do not know exactly how LMX and LID together explain leadership effects. In the interest of theoretical parsimony, one might argue that if one mediator has no incremental validity beyond the other, we may have a simpler account for leadership processes. To this end, Gottfredson and Aguinis (2017) conducted a meta-analysis based on multiple meta-analyses and found that, compared with other leadership mediators (e.g. job satisfaction, satisfaction with leader, role ambiguity, role conflict, trust, and justice), LMX was the most potent mediator between four positive leadership styles (consideration, initiating structure, transformational, and contingent reward) and followers’ task performance and organizational citizenship behaviors (OCBs). However, the authors did not include LID in their analysis. Thus, it is unclear how LMX and LID compare. Additionally, the relative validities of LMX and LID as leadership mediators may depend on the specific outcome variables studied (cf. Martin et al., 2016; Zhu et al., 2012). Hence, a more complete understanding of leader-follower relational influence should consider LMX and LID together with behavioral outcomes that are in sharper contrast with the more traditional performance variables (e.g. Chiaburu et al., 2014). We argue that LMX and LID each may motivate followers in distinct ways that foster different kinds of behaviors. Because motivation is better understood by considering what it predicts (Cerasoli et al., 2014), we focus on two distinct citizenship behaviors as outcomes to help differentiate LMX and LID. The first is helping, also called altruism, which refers to followers’ small acts that are cooperative and beneficial to others (Farh et al., 1997). The second is taking charge, a challenging type of OCB (Van Dyne et al., 1995), which denotes “voluntary and constructive efforts, by individual employees, to effect organizationally functional change with respect to how work is executed within the contexts of their jobs, work units, or organizations” (Morrison and Phelps, 1999, p. 403).