Without the help of many people this Special Issue could never have been produced. In addition to those who have contributed papers, we sincerely thank the following for their generous donations:

To the Yoruba people of South-West Nigeria, on the West Coast of Africa, death, or transition from one level of existence to another, is well accepted as part of life. Rites of passage are seen as an opportunity for saying farewell to the deceased and seeking their continuous protection of the living members of the families. After the death of a twin, a twin statuette, symbolically representing the departed twin, also acts as a companion and solace to the living twin. This paper examines these subjects including the special rites performed for twins, the relationship of the family to the deceased and the question of reincarnation

Estimates suggest up to 15% of multiples grow up as singleton survivors. Few studies have reported how bereaved multiple birth mothers with a surviving multiple cope with their bereavement. Using the population-based Western Australian Twin Child Health study database and other sources, we interviewed 66 bereaved mothers with at least one surviving multiple. For many, this contact was the first acknowledgement of their status as multiple birth mothers since their loss. The Beck Depression Inventory 2nd Edition (BDI) showed significant reduction in depression between the time of loss and our interview. For mothers as a group there was a high correlation between current and retrospective BDI, and retrospective BDI and all three Perinatal Grief Scales (PGS). There was a significant correlation between the three grief factors on the PGS. When subdivided, this held for mothers who suffered a loss at or before the neonatal period, but not for those whose loss occurred later. Bereaved mothers of multiples scored significantly higher on the PGS than the PGS norm for bereaved mothers of singletons, which we attribute to others not acknowledging their grief, and/or recruitment differences. There were no significant differences in PGS scores related to cause, the time since death, or sibling number or age. Spiritual beliefs and finding meaning in loss were positively related to scores for adjustment and acceptance. Although traumatised, most mothers accommodated their losses meaningfully in their lives. Their own support recommendations are included.

Following my own experience with the death of a twin baby, I founded the Center for Loss in Multiple Birth (CLIMB) Inc. During the last 13 years I have worked with nearly 7000 bereaved parents of twins, triplets or other high multiples throughout the US and worldwide. The role of a peer support organisation and the range of families with multiples who have contacted it is described. They come from diverse backgrounds with many forms of bereavement: death during pregnancy, at birth or after of both or all babies, of one twin, of one or more higher order multiples; multifetal pregnancy reduction or selective fetocide; the death of one or more multiples in childhood. Some have had more than one multiple pregnancy and loss. Many are concerned for the surviving children. A peer support organisation has an important role to play in increasing public awareness of the needs of these families as well as influencing policy on infertility treatments that carry a high risk of producing multiple pregnancies with the associated risk of death and disability for one or more of the babies.

From early pregnancy into childhood, higher multiples have much higher rates of mortality, whether from spontaneous abortion, the ‘vanishing twin’ syndrome, fetal or infant death. Many parents must cope with the death of one baby whilst the siblings remain critically ill or later become disabled and yet there grief is often underestimated. Little is known about the long term feelings of parents who choose to have a multifetal pregnancy reduction (MFPR). Most say they made the right decision but also that there was insufficient respect for their loss. They are often anxious about what, if anything, to tell the survivors and how they might react. Long term follow-up studies of the children as well as the parents are needed. Meanwhile parents who chose to have a MFPR must be given more information and ongoing support.

An analysis of coping, grief and health characteristics is reported for a bereaved monozygotic (MZ) and dizygotic (DZ) same-sex twin sample. The data were examined with reference to psychobiological and evolutionary perspectives on behavior. A Coping Scale, included as part of a comprehensive Twin Loss Survey (TLS), assessed coping with daily responsibilities and activities 1–2 months before the co-twin's death, 1–2 months following the co-twin's death and currently. A Grief Intensity Scale obtained judgments of grief 1–2 months following the loss, and currently. Information on physical symptoms was available from the Somatization Scale of the Grief Experience Inventory. Psychobiological and evolutionary perspectives specified hypotheses for two twin groups: one model was specified to reflect bereavement experiences immediately following loss of the co-twin (retrospective twin group); a second model represented present bereavement response (current twin group). Consistent with psychobiological theory, twins' social closeness showed a positive association with grief intensity which, in turn, affected somatic symptoms and coping efficacy in predicted directions. With respect to evolutionary psychological theory, the effect of zygosity on current grief implicated correlates of genetic relatedness as factors in the bereavement process.

The present study compared bereavement responses of 325 monozygotic (MZ) and 176 dizygotic (DZ) adolescent and adult twins following the loss of their co-twins. A subset of twins completed the Grief Experience Inventory using a retrospective time frame, while a second subset completed it using a current time frame. It was hypothesized that MZ twins (in both retrospective and current groups) would report higher levels of grief-related behavior than DZ twins, consistent with Hamilton's (1964) concept of inclusive fitness. Discriminant function and profile analyses yielded supportive findings, but only for the retrospective MZ and DZ twin comparisons. Females in both groups expressed higher levels of bereave-ment-related behavior than males. Findings are discussed with reference to theoretical aspects of grief and mourning.

Cultural beliefs about the nature of multiples appear in the mourning practices of many civilizations. Ethnographic literature suggests common themes that echo modern concepts. Many societies viewed twins as fragile, likely to die without preferential or meticulously equal treatment. A shared soul between twins is a common tenet, and the death of one is often felt to herald the other's prompt demise. The close relationship between multiples influences funerary rites. Honor, fear and mysticism are often evident in rituals. Twin infanticide was widely practiced, yet mourning customs were still observed. Many peoples recognize the special status of multiples and their families after one, two or more die.

Only recently has the special bereavement associated with the loss of a twin been generally recognised. With the notable exception of Joan Woodward, few have written on the subject. We, therefore, offer a shortened version of a paper written nearly 30 years ago. George Engel was himself a lone twin as well as being an eminent psychiatrist and psychoanalyst in the United States. The length of the paper precludes reprinting the totality but we hope readers will be encouraged to seek out the original published in The International Journal of Psycho-analysis in 1975, Vol 56 part 1, 23–40 .

Several studies have explored the impact of marital bereavement on mortality, while increasing emphasis has recently been placed on genetic factors influencing longevity — in this paper, we study the impact of losing the spouse and losing the co-twin, for twins aged 50 to 70. We use data from the Danish Twin Registry and the Population Register of Denmark for the period 1968 through 1999. Firstly, we use survival analysis to study mortality after the death of the spouse or the co-twin. We find that the risk of dying is highest in the first year after the death of the spouse, as well as in the second year after the death of the co-twin. We then use event history analysis techniques to show that there is a strong impact of the event ‘losing the co-twin' even after controlling for age, sex and zygosity and that this effect is significantly higher in the second year of bereavement. The effect is similar for men and women, and it is higher for monozygotic twins. The latter confirms the influence of genetic factors on survival, while the mortality trajectory with a peak in the second year after the death of the co-twin is consistent with the existence of a twin bereavement effect.

The primary foci of twin research have been on twins as a biological phenomenon, on the management of medical complications of twin pregnancy and birth and on the study of individual differences and development by psychologists and geneticists for whom twins provide a powerful research tool. The twin relationship — twinship — has received less research attention, including the aspect of bereavement which may occur at any stage of life. This paper presents some findings from a qualitative study that used grounded theory methodology to explore the nature of twinship especially issues relevant to psychological counselling with twins. Fourteen participants were interviewed in-depth about their understanding and experience of twinship. Participants were selected who had a rich knowledge and experience of twinship and of therapeutic work. Segments of transcribed interviews were constantly compared to describe and elaborate frequently repeated concepts in the data. Two of the main themes of discernment, the core category of the theory of twinship, are described. These are ‘defining boundaries’ and ‘managing ambiguity’. Aspects of these as experienced by twins are discussed in the light of current psychological theories about bereavement.

In this exploratory study of 15 families with a twin-pair, of which one has an intellectual disability, the Nijmegen Questionnaire on Childrearing Situations (NQCS) was used to ask mothers about their perceptions and experiences of parenting. An interview with the mothers was done to understand the initial stages of coping with this double problem: educating a twin-pair and a child with an intellectual disability. Four groups of mothers were identified, depending on whether they accepted the intellectual disability of their child and/or whether they perceived their children as a twin-pair or not. Finally, some critical questions for further research and management were formulated.

With the dramatic increase in the incidence of higher-order multiple pregnancies, more and more women are advised to consider undergoing multifetal reduction. However, little is known about the woman's experience of making the decision to undergo or forgo reduction. This study explored the experiences of seven women in making this decision and to identify any effects of it. Vivid descriptions emerged of multiple levels of bereavement. Several participants lamented that nothing occurred naturally in their pregnancies, from conception right through delivery and life with multiples.

We invited bereaved twins, parents of twins and carers to describe some of their personal experiences. We are grateful to all of them for their brave candour. We gave extra space to Kathy's story about the impacts of the loss of her own twin because it vividly illustrates the profound connections twinship can generate. Similarly we thought the cruelly long and complex saga of the life and death of Maxine's twins could help understanding of the distressing repercussions that often attend the low birth weight and prematurity that are so common amongst multiple births.