Abstract: This study aims at identifying the main factors affecting design quality, identifying the main factors affecting material waste and addressing the relationship between design quality and waste on construction sites in residential building projects in Palestine. To identify the main factors of deign quality and material waste, a questionnaire survey is conducted. Fifteen ( factors of design quality and 15 factors of material waste are identified from literature review and feedback from local experts. A questionnaire is designed to include these factors. Targeted population included contractors and consultants who have experience in residential projects. Forty-five contractors and 35 consultants rank the identified factors according to their importance. The study reveals that the top factors of design quality are: lack of staff experience, inadequate time given for design, payments delay for design services, owners award bids for lowest price designer and copying and modifying from previous designs. It also indicates the significant factors of material waste). Include: design mistakes, late design changes, rework, lack of labor experience and purchasing materials not complying with specifications. Based on data collected from 33 building projects, a predictive model is established. The model indicates a good relation between material waste and design quality.