This article analyses defence and security spending (DSS) in Colombia, on the assumption that in order to gain a better idea of the effect of such spending on economic growth and the public finances it would be desirable to analyse its internal composition, since this would make it possible to infer its impact on the production of defence and security. In order to do this, various theories on the repercussions of military expenditure are reviewed and defence and security spending in Colombia is analysed on the basis of information from the Office of the Comptroller-General of the Republic. The efficiency of spending on the armed forces and the National Police is then examined, especially as regards the relations between combat and support and attack and defence, and it is shown that the military forces need to be reorganized. In the conclusions, various ways of securing savings on the defence budget are proposed. The most important of these are connected with personnel management, as payroll expenses represent 73% of total spending. The proposals made in this respect are to modify the system of pay and allowances, increase the retirement age, reduce the number of personnel and restructure the proportions between combat forces and support and administrative personnel.