The anatomy of disadvantage in Chile and in Santiago is a product of a long history and is broad and deep, with great income inequality and widely dispersed populations. These conditions are also not unusual in other middle-income countries and fast growing economies, many of which are also investing heavily in urban transport systems at this time. In the mid-2000s, in an effort to confront some of these problems, there was a large expansion of Santiago’s (Chile) subway network (Chapter 2). This thesis investigates the socioeconomic impacts of the much-improved urban transport accessibility. This expansion occurred within a short period of time (2004 through 2006). Because of a conjunction of efforts by the Chilean government to evaluate the effectiveness of the country's social policies, there is much data available characterising the socioeconomic conditions both before and after the expansion. For example, in this thesis I use a panel survey with circa 5000 interviewees with labour market outcomes, administrative panel data with standardised test scores of 100,000 students in eighth grade, and police crime records with all reported crimes to the police in Santiago. To control for workers (Chapter 4), students (Chapter 5) and small crime areas (Chapter 6) individual and unobserved characteristics that do not change in time, I use a fixed-effects method. Depending on the outcome, the unit of observation was an individual or a spatial unit. In addition, to allow for differential pre-existing trends in the outcome variable, in the first-differenced form I control for relevant baseline characteristics. There are three socioeconomic conditions examined in detail in this thesis. These are impacts on the labour market (in Chapter 4), student achievement (in Chapter 5), and property crime (in Chapter 6). In Chapter 4, my general findings are that greater proximity to the subway network increases labour market participation, employment hours, and labour earnings. However, the main policy implication of this part of the study is that accessibility of transportation is a crucial factor affecting the female employment rate. This is extremely important in cities with a low female employment rate and a low or non-existent coverage of rapid transit systems such as subways. In Chapter 5, I find that increased proximity to the subway network is associated with substantially lower test scores. Policy implications to consider are that schools that will soon be more accessible to rapid transit systems should consider the possibility of undesired increases in class sizes due to more demand because of the increased availability of nearby rapid transit stations. In Chapter 6, I find that greater proximity to subway stations increased both robbery and larceny in the public space within one year after the opening of the subway stations. One policy implication is that the police should redistribute its personnel whenever the flows of pedestrians and commuters may be affected because of changes in the transport network. In light of the well-established fact that citizens appreciate improvements in the subway network that increase their accessibility to employment and to services in general, this thesis provides evidence that a relevant advantage of better urban transport is an improvement in labour market conditions.