Political par ties are central actors within western Euro pean polit ical sys tems, and the choices they make in terms of elect oral, parlia ment ary and governing strat egies can signi fic antly influence their success or failure as polit ical actors. It may be a truism that par ties compete for ‘pol icy, office and/or votes’ (Müller and Strøm 1999b), but exactly how polit ical par ties compete and, more specifically, what impact the com petit ive choices made by polit ical par ties have on their own fate, and the party sys tems in which they compete, remains an understudied area of research. The significance of party strat egies has been highlighted in the work of Müller and Strøm (1999b) among others, and the role that polit ical par ties can play in the pro cess of party sys tem change has also been highlighted, most notably by Peter Mair (1997, 2002). However, the work of Müller and Strøm does not con sider the sys temic impact of a party’s stra tegic choice and the impact that these choices can have on party com peti tion. In contrast, the work of Mair focuses on the role of polit ical par ties in the pro cess of party sys tem change, but does not con sider in detail the stra tegic de cisions and actions that influence party beha vi our, ultimately influ en cing the shape of the party sys tem. This book seeks to fill a gap in the liter at ure by de veloping the work of Mair, and Müller and Strøm to combine these approaches and to address specifically how estab lished polit ical par ties may seek to influence the pro cess of party sys tem change, and with what impact. The im port ance of party strat egies has become an increasingly pertinent research question since the 1970s, when the dawning of the ‘post industrial’ age (Bell 1973) substantially changed the polit ical landscape in which polit ical par ties acted and competed. Sustained peace in western Europe, unparalleled prosperity, a vast expansion in higher education and increased travel and communication between coun tries (Crewe 1985: 5) led to changes at the societal level that signi fic antly altered elect oral beha vi our. The votes of par ties’ core sup porters were no longer as sured, and the erosion of societal cleavages facilitated the pro cess of party sys tem frag menta tion. Indeed, since the 1970s, there has been an increase in the frag menta tion of party sys tems (Wolinetz 1979), elect oral volatility (Pedersen 1979), partisan dealignment (Dalton et al. 1984), decreasing elect oral turnout (Franklin 2004) and declining party mem ber ship (Mair and Van Biezen 2001) across western Europe. However, this is not to say that polit ical par ties have acted solely as passive vic tims of the pro cess of rad ical change.