Monitoring can be defined as: “A continuing function that uses systematic collection of data on specified indicators to provide management and the main stakeholders of an ongoing development intervention with indications of the extent of progress and achievement of objectives and progress in the use of allocated funds”. See Organisation for Economic Co-operation and Development (OECD), Glossary of Key Terms in Evaluation and Results Based Management (Terms are presented in English, Chinese, French, Italian, Japanese, Portuguese, Russian and Spanish.) Thus monitoring embodies the regular tracking of inputs, activities, outputs, outcomes and impacts of development activities at the project, program, sector and national levels. This includes the monitoring of a country’s progress against the millennium development goals (MDGs), or other national measures of development success.

Evaluation can be defined as “the process of determining the worth or significance of a development activity, policy or program ….. to determine the relevance of objectives, the efficacy of design and implementation, the efficiency or resource use, and the sustainability of results. An evaluation should (enable) the incorporation of lessons learned into the decision-making process of both partner and donor”.

Monitoring and evaluation are synergistic. Monitoring information is a necessary but not sufficient input to the conduct of rigorous evaluations. While monitoring information can be collected and used for ongoing management purposes, reliance on such information on its own can introduce distortions because it typically covers only certain dimensions of a project’s or program’s activities, and careful use of this information is needed to avoid unintended behavioral incentives. In contrast, evaluation has the potential to provide a more balanced interpretation of performance. But evaluation is a more detailed and time-consuming activity, and because of its greater cost it needs to be conducted more sparingly. One approach is to rely on monitoring information to identify potential problem issues requiring more detailed investigation via an evaluation.

M&E can be conducted using a wide array of tools, methods and approaches. These include, for example: performance monitoring indicators; the logical framework; theory-based evaluation; formal surveys such as service delivery surveys, citizen report cards, living standards measurement surveys (LSMS) and core welfare indicators questionnaires (CWIQ); rapid appraisal methods such as key informant interviews, focus group discussions and facilitated brainstorming by staff and officials; participatory methods such as participatory M&E; public expenditure tracking surveys; rigorous impact evaluation; and cost-benefit and cost-effectiveness analysis.

Monitoring and Evaluation: Some Tools, Methods and Approaches
Impact evaluation offers the most rigorous - and most expensive - techniques for identifying the precise efforts of a program or activity. See Conducting Quality Impact Evaluations Under Budget, Time and Data Constraints
And IEG’s Impact Evaluation and Evaluation Training websites