The purposes of an evaluation will inform (and be informed by) the evaluation timelines, resources, stakeholders involved and choice of evaluation options for describing implementation, context and impact.

It is not enough to state that an evaluation will be used for accountability or for learning.  

Evaluations for accountability need to be clear about who will be held accountable to whom for what and through what means.  They need to be clear about whether accountability will be upwards (to funders and policymakers), downwards (to intended beneficiaries and communities) or horizontal (to colleagues and partners).

Evaluations for learning need to be clear about who will be learning about what and through what means. Will it be supporting ongoing learning for incremental improvements by service deliverers or learning about 'what works' or 'what works for whom in what circumstances' to inform future policy and investment?

It may be possible to address several purposes in a single evaluation design but often there needs to be a choice about where resources will be primarily focused,

Options

Using findings

• Contribute to broader evidence base: inform future policy and practice by others outside the organization
• Inform decision making aimed at improvement (formative): changing or confirming policies and practices
• Inform decision making aimed at selection, continuation or termination (summative): identifying best value for money
• Lobby and advocate: justify expenditure and demonstrate achievements

Using process

• Build trust and legitimacy across stakeholders: develop better understandings of each other and demonstrate that expectations are being met
• Ensure accountability: holding someone to account to someone for something
• Ensure diverse perspectives are included, especially those with little voice: make explicit the experiences and values of key stakeholders, especially intended beneficiaries

Resources

• Accountablility and Learning, - Irene Guijt.  This discusses potential conflicts between designing evaluations for accountability and for learning, and how to resolve these,
• Purposes of Assessment - Keystone Accountability.  This discusses six major reasons why social organizations monitor, assess and report on their performance and results. 
• Seeking Surprise: rethinking monitoring for collective learning in rural resource management- Irene Guijt. This discusses nine different learning purposes, and how monitoring and evaluation systems can be constructed to support them.
• Utilization-Focused Evaluation - Michael Patton. The UFE approach is based around identifying primary intended users and uses and basing all decisions about the evaluation on addressing these.  It includes a discussion of possible intended uses.