The lack of attention to quality control by house builders in the Australian State of Victoria has been a contentious issue for more than two decades. Ina an attempt to improve the quality of housing, various mechanisms such as voluntary and compulsory registration schemes have been adopted and discarded by industry-based organisations and government. While builders are encouraged to improve construction quality, little is known and published about the quality of housing produced by owner builders specifically during the seven year warranty period after construction is completed. With this in mind, this thesis presents research findings that compare the latent defects in houses built by owner builders with those of registered builders. Using inspection reports provided by Archicentre <a subsidiary of the Royal Australian Institute of Architects> a sample of 1772 houses, of which 1002 were owner builders <HO> and 770 were registered builders <HR> was used to determine the severity, the incidence, and location of defects within each house type. Houses less than a year old were found to contain a siginificant proportion of defects for both types of builder. In addition, it was found that HO builders had a mean of 2.74 defects per house and HR builders mean of 2.30 defects per house for the seven-year warranty period. To determine whether there was a significant difference between the quality of housing produced by HO and HR the statistical technique of Chi-squared analysis was undertaken at a 5% level of significance. The analysis revealed that there was a significant difference between the quality of housing procured by owner <HO> and registered <HR> builders. In particular, it was found that the important category of workmanship for HO builders had significantly less defects that HR builders, which suggests that HR builders need to improve their managerial practices and the quality of on-site supervision. In essence, this thesis has provided a series of benchmark metrics for latent defects against which current and future legislative programs con be compared for new housing in the State of Victoria. It is recommended that future research focus on the methods for improving the role of the on-site supervisor as they are considered to be the important link in the quality chain.