A longitudinal study of firms that are in the process of being established (nascent firms) and firms that have recently been established (young firms). The datasets comprise 1412 qualifying cases (obtained from a screening sample of 30,430 randomly selected households in Year 1). The data were collected in 4 annual waves each with over 500 variables per record, plus a fifth, follow-up wave focusing on outcomes. Wave 1 completed in May 2008; Wave 2 completed in July 2009; Wave 3 was completed in July 2010 and Wave 4 in July 2011. Wave 5 (outcomes follow-up) was completed in late 2013. The comprehensive data were collected by computer-aided telephone interviews (CATI) (approximately 45 minutes for each interview) and have been converted into SPSS and data base formats. There is extensive documentation on the dataset in the related codebook. The data set and documentation are available at http://eprints.qut.edu.au/49327/.