ISO/IEC 15504 also known as SPICE

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ISO 15504

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ISO/IEC 15504 also known as SPICE (Software Process Improvement and Capability dEtermination) is a "framework for the assessment of software processes" developed by the Joint Technical Subcommittee between ISO (International Organization for Standardization) and IEC (International Electrotechnical Committee). For more information about the SPICE project documents: The_SPICE_project





The ISO/IEC 15504 framework does not set out specific standards. Other, more specific standards, set out requirements for (say) a valid test plan. What ISO/IEC 15504 is concerned about is the capability provided by the organization's management and process definition structures.

ISO/IEC 15504 is not a methodology. Although ISO/IEC 15504 sets out a list of activities that might (and should) occur in a software project, it does not set out the order in which such activities should be carried out.

ISO/IEC 15504 is, in effect, a set of categories (pigeon holes) in which the assessors can place the evidence that they collect during their assessment, so that the assessors can give an overall determination of the organisation's capabilities for delivering software.

The ISO/IEC 15504 standard

The actual standards document for ISO/IEC 15504 is divided into 9 parts.

Part 1 of ISO/IEC 15504 explains the concepts and gives an overview of the framework.

Reference model

ISO/IEC 15504 contains a reference model. The reference model defines a process dimension and a capability dimension.

The reference model is the subject of part 2 of ISO/IEC 15504.


The process dimension defines processes divided into the categories of:

  • customer-supplier
  • engineering
  • supporting

Capability levels

For each process, ISO/IEC 15504 defines a capability level on the following scale:

Level Name
5 Optimizing process
4 Predictable process
3 Established process
2 Managed process
1 Performed process
0 Incomplete process


ISO/IEC 15504 provides a guide for performing an assessment.

This includes:

  • the assessment process
  • the model for the assessment
  • any tools used in the assessment
  • success factors

Performing assessments is the subject of parts 3 and 4 of ISO/IEC 15504.

Assessment model

The assessment model is the detailed model that is used for an actual assessment. This is an elaboration of the reference model.

Part 5 of ISO/IEC 15504 provides an assessment model, but other models could be used instead, if they meet ISO/IEC 15504's criteria.


For a successful assessment, the assessor must have a suitable level of the relevant skills.

These skills include:

  • personal qualities such as communication skills
  • relevant education and training and experience
  • specific skills for particular categories, e.g. management skills for the management category.
  • training and experience in software capability assessments.

The competency of assessors is the subject of part 6 of ISO/IEC 15504.

Uses of ISO/IEC 15504

ISO/IEC 15504 can be used in two contexts:

  • Process improvement, and
  • Supplier evaluation.

Process improvement

ISO/IEC 15504 can be used to inform process improvement within a technology organization. Process improvement is always difficult, and initiatives often fail, so it is important to understand the initial baseline level, and to assess the situation after an improvenent project. ISO 15504 provides a standard for assessing the organization's capacity to deliver at each of these stages.

In particular, the reference framework of ISO/IEC 15504 provides a structure for defining objectives, which facilitates specific programmes to achieve these objectives.

Process improvement is the subject of part 7 of ISO/IEC 15504.

Supplier evaluation

An organization considering outsourcing software development needs to have a good understanding of the capability of potential suppliers to deliver.

ISO/IEC 15504 can also be used to inform supplier selection decisions. The ISO/IEC 15504 framework provides a framework for assessing proposed suppliers, as assessed either by the organization itself, or by an independent assessor.

The organization can determine a target capability for suppliers, based on the organization's needs, and then assess suppliers against this profile. This is particularly important in contexts where the organization (for example, a government department) is required to accept the cheapest qualifying tender. This also enables suppliers to identify gaps between their current capability and the level required by a potential customer, and to undertake improvement to make the contract.

Supplier process capability determination is the subject of part 8 of ISO/IEC 15504.

Part 9 of ISO/IEC 15504 is a vocabulary list.


A joint technical committee of the ISO and the International Electrotechnical Commission (IEC) known as JTC/SC7 developed the first version of ISO 15504 during 1991 to 1998 which has now been re-published during 2003 to 2005 .

Relationship to other frameworks

ISO/IEC 15504 derives from ISO 12207.

CMMI uses many of the ideas of ISO/IEC 15504.

Take up of ISO/IEC 15504

ISO/IEC 15504 has been very successful as:

  • ISO/IEC 15504 is publicly available through National Standards Bodies.
  • It has the support of the international community
  • Over 4000 assessments have been performed to date
  • Major sectors are leading the pace such as automotive, space and medical systems
  • There have been many international initiatives to support take-up such as SPICE for small companies

On the other hand, ISO/IEC 15504 has not been very successful, as compared to the CMM. This has been for several reasons:

  • ISO/IEC 15504 is expensive and not readily available. CMM and CMMI are available as free downloads from their sponsor's website.
  • The CMM is actively sponsored (by the US Department of Defense).
  • Most US corporations prefer the CMM because it is American.
  • The CMM was created first, and reached critical 'market' share before ISO 15504 became available.
  • The CMM has subsequently been replaced by the CMMI, which incorporates many of the ideas of ISO/IEC 15504, but also retains the benefits of the CMM.

Like the CMM, ISO/IEC 15504 has been couched in a military and aerospace context, making it difficult to apply ISO/IEC 15504 in a financial services context