Why does the rate of economic growth vary from country to country over long periods of time? Many empirical studies have attempted to answer this question by identifying the underlying factors that determine this growth rate. Most of these empirical studies have in common that only a few explanatory variables are included in their analysis but differ in the variables selected. This study will include some of the most common variables found in previous articles, such as: investment rate, government spending, inflation, openness rate, life expectancy and fertility, but differs by the addition of investment variables foreign direct, education spending and health spending in the analysis. The motivation behind the inclusion of these specific explanatory variables is due to the lack of conclusive findings in previous literatures and the absence of examining whether these variables have a significant effect on the growth rate of GDP per capita. This article differs from existing literatures in that the grouped countries data used in the study will be split into two additional OLS regressions classified by 34 OECD member countries and 34 developing countries. The aim is to see if there is clear evidence of the relationships between the variables and the economic growth rate of the two groups and how they differ. The paper will be divided into five sections: The next section will consist of analysis and comparisons of previous studies in the form of a literature review. The third section will explain the key variables and data of this study as well as a preliminary analysis in the form of a descriptive statistics table and a correlation matrix. The fourth section will cover the specific methodology, including the reasoning behind the middle of the article......ator used for its regressions are in fact robust and its results suggest that a more open country will experience growth of faster productivity. , thereby increasing the rate of economic growth. Historically, academics and policymakers have devoted considerable energy to the question of whether openness is good for growth. Most evidence is based on regression analysis, but this is heavily affected by endogeneity issues. An important article by Rodriguez and Rodrik (2000) criticizes the findings of a number of statistical studies that openness is associated with higher growth rates. They show that openness in the sense of liberal trade policies does not seem to guarantee faster growth rates. For the most part, they argue, "the nature of the relationship between trade policy and economic growth remains a very open question" (Rodriguez and Rodrik, 2000, p..266)