Abstract: The present disclosure provides methods for generating induced cardiomyocytes and/or inducing a cardiomyocyte phenotype in cells in vivo or in vitro, such as by expression of ASCL1 or MYF6 and MYOCD. The present disclosure further provides gene-delivery vectors comprising one or more polynucleotides selected from ASCL1, MYF6, MYOCD, MEF2C, and TBX5. It further provides compositions comprising induced cardiomyocytes and provides methods of treating a heart condition, such as myocardial infarction. The disclosure also provides engineered myocardin proteins with an internal deletion, vectors encoding such engineered mycocardins, and methods of use thereof.