The evaluation community of the US continues to be the largest and most influential but, while evaluation is becoming international, it is also becoming 'indigenous', meaning that 'evaluators around the world are developing their own infrastructures to support their endeavors as well as their own preferred theoretical and methodological approaches' (Chelimsky 1997: xi-xii).

According to one simple and general view, evaluation can be lagerly understood as the response to a demand for increased efficiency in the public sector. Thus, evaluation emerges because it is needed.

Although this functionally oriented explanation suffers from 2 deficiencies:
1) the evaluation wave began in the 1960s in a period of growth
2) it is not easy to demonstrate that evaluation actually does increase efficiency.

As an implication, evaluation as a field incorporates a numer of interesting tensions:
- alleged focus on effectiveness vs the effectiveness of evaluation itself hardly needs to be demonstrated;
- particular regimes of evaluation (incl. say performance indicators) vs the broader cultural claim to the contingency and fragility of practically every social construction (Stehr 2001) including systems which monitor performance indicators.
- more often than not, a critical discussion of existing evaluation practices has led to new models and approaches within the field > dynamic and diverse wave of evaluation.