Despite the growing literature that collaboration is a 'good' thing, there
are calls emphasising the need for evidence of its effectiveness. However,
the nature of the evidence to assess effectiveness is less clear. This pape
r examines the components that contribute to the challenges that confront e
vidence on collaboration. It considers the differing interpretations that h
ave been placed on evaluation and explores how ways of determining the outc
omes of collaboration and the levels of outcome measurement to assess colla
borative effectiveness are influenced by the multifactorial nature of the c
oncept. Evidence on the impact of collaboration is influenced by the divers
ity of perspectives and conceptual facets, and difficulty in measurement of
the notions involved. Other factors discussed are the choice of macro or m
icro evaluation, of proximal or distal indicators, of short and long-term e
ffects, or of individual-level or collective community-level outcomes. The
suitability of randomised controlled trials for the measurement of collabor
ative outcomes as well as the requirement of mixed methods evaluations are
highlighted. An evaluation of five community partnerships in South Africa i
s employed as an example to link the evaluation concepts that are discussed
to a real enquiry. If collaboration is to be successful in making a differ
ence in the lives of people, then increasing the precision and context of a
ppraising its effectiveness will reduce the nature of inconclusive evidence
and is likely to improve the practice of partnerships, coalitions and join
t working in health and social care.