This book constitutes the refereed proceedings of the First International Rapid Mashup Challenge, RMC 2015, held on June 23, 2015, in Rotterdam, The Netherlands, in conjunction with the 15th International Conferenceon Web Engineering, ICWE 2015.The 2015 edition of the challenge is the firstinstallment of a series of challenges that aim to engage researchers andpractitioners in a competition for the best mashup approach. The 6 thoroughlyreviewed contributions contained in this volume are extended versions of theinitial proposals that served the authors to express their interest toparticipate in the challenge. The initial proposals have been used by thechallenge organizers to select participants based on the interestingness andmaturity of the proposals.