This publication provides for the main contributions of the APEC Seminar on Economic Analysis in Horizontal and Non-Horizontal Mergers held in Santiago, Chile, on 28 February and 1 March 2019. The seminar allowed participants to discuss the strengths and weaknesses of different tools used to measure the potential competitive impact of horizontal and non-horizontal mergers. The aim was to evaluate the importance and validity of simpler tools that are commonly used to identify which mergers are likely to present more risks. It is intended to provide a record of those contributions in furtherance of the objectives of the workshop. Twelve presentations were given at the workshop by experts of the academia, providing the technical and analytical views of the use of these different tools. Also, presentations from the approaches taken to merger review in seven APEC member economies were provided, namely: Australia; Canada; Chile; Japan; Mexico; Russia; and the United States.