Purpose: The purpose of this paper is to estimate the extent of "over-qualification" (i.e. holding a qualification which is above that required to gain entry to the job being done) and "skills under-utilisation" (i.e. being in a job which does not make use of the knowledge and skills possessed) in the United Kingdom and to examine whether these conditions are correlated with age. Design/methodology/approach: The paper makes use of the 2006 Skills Survey. Cross tabulations of both conditions with age are produced and binomial probit estimates of both conditions are reported. Findings: It is estimated that 38 per cent are over qualified; 15 per cent are in jobs which do not make use of the knowledge and skills they possess; and age is correlated with the probability of being over qualified but not with the condition of under-utilising the knowledge and skills possessed. Social implications: Skills policy in the United Kingdom focuses almost exclusively upon increasing the supply of more highly qualified individuals. Given the extent of over-qualification and skills under-utilisation demonstrated in the paper, more effort should be made by policy makers to design and implement policies which increase the demand for highly skilled labour. Originality/value: The paper answers three questions: How prevalent are qualification mismatches? How prevalent are skills mismatches? To what extent are the two conditions of being over-qualified and being in a job which does not offer scope to make use of the knowledge and skills possessed correlated with age? (Contains 7 tables and 3 notes.)