This book gives an up to date reference on the state of the art in this highly important methodological area, which is central both to theoretical models of party competition and to empirical accounts, whether these are case studies or comparative analyses. It looks at subjects including tracking estimates of public opinion and party policy intentions in Britain and the USA; the policy space of party manifestos; and party platforms and voters' perceptions. Its panel of respected contributors reviews the refinements which have been made to established techniques as well as considering the potential and early successes of computer coding.