The education debate can sometimes treat attendance, SEND and low attainment as distinct policy problems, with their separate funding streams, official guidance, public consultations and statistical releases. But our new research, co-published with the Education Endowment Foundation, suggests that these are all-important and most likely inter-related contributions to the accumulation of disadvantage through childhood and into adolescence. Using linked administrative data, we can unpick the most important contributors to the disadvantage gap in attainment and show how these evolve as children progress in their education. This clearly points to earlier attainment, particularly in maths and English, SEND and absence as critical pathways through which disadvantage shapes the gap. The idea that early intervention is key to gap-narrowing is hardly groundbreaking, but our research allows us to say exactly how much of the gap has opened at earlier ages and the role of individual subjects. Forty per cent of the key stage 2 gap (of 10.1 months) is explained by lower attainment among disadvantaged children in reception year in just three early years subjects: literacy (adding 1.9 months to the gap) maths (1.3 months), and communication and language (1.0 month). By the end of secondary school, the GCSE gap is 17.9 months. Almost half of this gap has already emerged by the end of primary school, with pupils’ key stage 2 attainment strongly linked to later outcomes. Maths makes the largest contribution, adding 3.6 months to the GCSE gap, followed by reading (1.8 months) and grammar, punctuation and spelling (1.5 months). We also find that doing well earlier in primary school, up to age 7, appears to protect against further gap-widening later on, even after taking account of attainment at older ages. Perhaps where the messaging around early intervention comes through most strongly is our analysis of SEND. Largest measurable contributor The headline here is that SEND is central to the gap story. It is the largest measurable contributor to the age five gap and the second largest at key stage 2, while much of its influence at later ages seems to operate indirectly through prior attainment and attendance. But beneath this headline, we also find cause for cautious optimism. Where SEND is identified early and support is sustained, pupil outcomes can look very different, and in some cases comparable to peers without SEND who have similar starting points. The third stand-out contributor to the gap, particularly as pupils get older, is absence. We find that the higher level of absence of disadvantaged pupils contributes one-fifth of the key stage 2 gap, rising to one-third of the GCSE gap. Importantly, the story is not only about persistent or severe absence. Even moderate absence is associated with almost two months’ lower attainment at key stage 2 and almost six months at GCSE, compared to similar pupils with absence rates below the national average. We also consider how the gap evolves for persistently disadvantaged pupils. These pupils, who are eligible for free school meals for at least 80 per cent of their time at school, face an even wider GCSE gap of almost two years. But they attract no additional funding under the current system. The same pathways are evident as for disadvantaged pupils overall. But the challenges related to low prior attainment, SEND and absence are more acute. Most strikingly, persistently disadvantaged pupils have already fallen behind other disadvantaged pupils during their first year at school. The central implication of our research is that we cannot consider, let alone tackle, these challenges separately. If the government is to make meaningful progress towards its target to halve the disadvantage gap, it must be guided by evidence on what drives it. Collective action With support from the sector and families, the government needs to adopt a joined-up approach involving both earlier intervention and sustained support. This collective action must address the interwoven issues that contribute most to the gap: early childhood inequalities, SEND and absence. It will require a strategic approach across complex, concurrent reforms including disadvantage funding, SEND and new area-based missions. But history tells us that, with long-term investment and a commitment to stay the path, progress in gap-narrowing is possible.