The writer is a specialist adoption worker for the London Borough of Greenwich.

IF YOU ask yourself why people want to become parents, you might come up with some of the following reasons: to continue the family line; to give and receive love and gain personal fulfilment; to mould a child. Everybody does it and it's difficult to be the odd one out. We embark on family life with these and many more hopes and expectations.

In adoption, the social worker and prospective adoptive parents work together over many months to see if their needs can realistically be met by adoption, and to gauge whether they are compatible with the needs of children, most of whom have had such painful and damaging experiences that the courts have decided that they should be removed from their families. You need more than common sense and an abundance of love to be able to cope with a child suffering the trauma of separation from familiar, even if abusing, people and places.

The preparation process that leads to the compilation of the standard British Agencies for Adoption and Fostering assessment form is a two-way process of exploring the applicants' motivation, background, experiences, capacity to deal with often difficult and disturbed behaviour and ability to stick by a child (often with little reward), and jointly identifying the age, behaviour and genetic background that they would consider.

The process entails individual sessions with a social worker, group meetings with other applicants, reading and watching videos, examining case studies, and contact with specialist agencies in such fields as mental health, genetics and special needs. Would-be parents are also referred to support groups for adoptive families and post-adoption centres: many applicants are stunned to learn of the experiences that children have been through, and the impact that this can have on their ability to form strong attachments to a new family.

Now that there is less stigma attached to single parenthood and women have more control over their fertility, babies are rarely given up for adoption at birth. Adoption is now a service for children who have often experienced more trauma than most people have in a lifetime.

They are not grateful to have new parents, but full of distress and self- blame for having lost their birth parents, and they are often difficult to live with. They may soil themselves, smear excreta on the walls, play one parent off against the other, lie or tell the new parents they hate them.

Such behaviour is difficult to cope with and new parents who, understandably, hope to be rewarded with love and gratitude, may be disappointed and find they are not up to such a demanding job.

Providing emotional nourishment to these children is far from straightforward. They have a right and need to know about their birth families, to have their life-stories explained to them throughout their childhoods, to have their parents' actions or ill-health expressed in a blameless way. If you tell a child their parent is 'bad', they may fear that they are bad, too.

The majority of our applicants come to us after many disappointing years of treatment for infertility. They feel an urgent need to become parents and can sometimes regard the social worker sent to assess them as an obstacle between them and their goal. This and their often unresolved feelings about infertility can cloud their ability to use the adoption process to look objectively at what they can offer a troubled child.

If a couple have not come to terms with their inability to have a child, they may find themselves investing in the adopted child all the natural hopes and expectations of a new parent without accepting and acknowledging the child's background. Adoptive parents need to be able to accept a child with a different history, a different inherited personality type, different physical characteristics and a different family living somewhere else, with whom adopters are encouraged to meet and sometimes have ongoing contact.

Some applicants withdraw during the preparation, realising that adoption is not going to meet their needs. Sometimes the agency decides not to progress. This can be for many reasons; underlying marital problems, poor health prognosis, or an inability to understand the needs of children in care who suffer from low self-esteem and whose innocent trust in adults has been destroyed.

Adopters are ordinary people with special qualities. They don't have to be wealthy, have a big house and a high-status job, or be under 35. They just have to accept a child as he or she is and be there to parent them into adulthood.

Fortunately for many children, and particularly for the 20 to 30 we place a year, there are such families around.