In fact, this book is a PhD research submitted to the Universiti Sains Malaysia, Penang in 2011. The book's title is taken from a PhD work entitled"IMPACT OF SPATIAL CONFIGURATION ON FUNCTIONAL EFFICIENCY OF HOUSE LAYOUTS IN ERBIL CITY, IRAQ FROM 1900 TO 2010" which was invented a new method for measuring the impact of spatial configuration on functional efficiency of house layouts in the city of Erbil, Iraq for the period 1900-2010. This period has been divided into four time periods, each period extends to 40 years as follows: first period(1900-1930); second period(1930-1960);third period(1960-1990);fourth period(1990-2010). Space syntax methodology and its techniques has been applied depending on the software program A-Graph. For the purposes of the study, evaluation and comparison more than 1,000 house layouts has been surveyed, from this sample 160 house layout applied in the process of evaluation, representing 40 house layout for each period. The content of this book is an effective contribution in clarification the effect of spatial configuration on the efficiency of house layouts in terms of their functionality due to transformations and changes occurred over time.