A necessary clarification to begin with: this outstanding tour de force of a monograph has had a misleading title foisted upon it by the publishers. It is not about children and religious dissent in general, nor, as the D-word might suggest, about Protestant nonconformists, but wholly and almost exclusively about children and Roman Catholicism. The title of the doctoral thesis on which it is based makes that clear, and so too does Underwood's dedication: ‘To the recusants. Every last obstinate Popish one of them’. That also tells the reader that we are in for a lively ride. This is punchy stuff, and Underwood is enjoyably ready to take a swing at historians with whom she disagrees. In another age, she would have made a good religious polemicist.

In this one, what she has written is an ingeniously and exhaustively researched study of a subject which we had thought was largely irrecoverable, collecting some very scattered and fragmentary evidence to do so. The book falls into three parts. The first (and strongest) contains three chapters looking at children's upbringing in and conversion to Catholicism. This is built chiefly around the testimonies given by entrants to the English Colleges in Rome and Valladolid, a rich seam of material which gives an almost unparalleled insight into the recollected religious lives of a group of English children, and which Underwood handles deftly and subtly. Her Catholic children slowly grow up into their recusant inheritance and its burdens, and their parents negotiated the degree of Protestant influence to which it was safe to expose them. The community worked to shape its next generation: keeping fast days may not have been a strict obligation for Catholics at risk of persecution, but it was essential for maintaining a clear sense of identity. Likewise, it appears that mothers frequently contrived to give birth away from home, so as to evade Protestant baptisms – which were sacramentally valid, but stank of participation in heresy. We learn about children's reading matter, of all kinds, and about the influence of siblings as well as of parents. Underwood is characteristically sharp on the ‘studied naïveté’ (p. 55) of Catholic catechesis, whose pretence that there had been no Protestant Reformation was not denial but a steady insistence that the world in which English Catholic children were being raised was an aberration.

Many of these children came from Catholic families, but many did not, and many who did still had experiences which they saw as conversions. Some paths were winding ones: one Nicholas Hart converted initially because he feared being killed in a duel and wanted some spiritual life-insurance, before a separate, moral conversion more than a year later. Other cases were straightforward. It appears that the Puritan Thomas Rogers was right to worry that Robert Persons's Book of resolution, even in the bowdlerised Protestant edition, was luring readers to Rome: for one Thomas Pennant read it as an ‘atheist’, was stricken, and headed straight for Rome to consult Persons ‘about how to pass the rest of my life in the service of God’. ‘Any author’, Underwood comments, ‘would call that a result’ (p. 42).

By the early seventeenth century, it seems, fewer students at the English Colleges were self-described converts, which she suggests may mean that inter-generational transmission of the faith was working more smoothly. The book's second part looks at the Protestant confessional state's haphazard attempts to disrupt that transmission. Wardship was one obvious mechanism for doing this, and some attempts were made to use it in this way, especially after 1620 and especially when – as occasionally happened – an individual bishop chose to make an issue of it. Or there could have been more generalised attempts to ‘rescue’ children from known recusant families, a policy which some Protestant agitators repeatedly and vainly called for during the period 1560–1640. The Commonwealth government after 1649 made the first serious attempt to do this, and discovered that it was much harder than it looked. It is not simply that no early modern state had the resources to police family life that closely, but that the policy directly cut against the truism that the household was a divinely-ordained model of Christian society. William Cecil contemplated attempting it in 1592–3, but decided both that it would fail and also that it would ‘make our Government odious’ (p. 110). No Protestant regime renounced the right to protect its subjects from the form of child abuse known as a Catholic upbringing, but most of the time this was a threat which Catholics could avoid or negotiate away, and so – usually – a headache rather than an existential danger. After the Restoration, even the ambition seems to have been abandoned.

The book's final part focuses on teenagers and ‘youths’: how Catholic adults tried to speak to and win them over, and how they claimed agency for themselves. This is more well-trodden ground than the previous two sections, but there are still worthwhile insights. The contested significance of the child as a polemical symbol is one. Everyone, naturally, wanted to be childlike but not childish. But, for Catholics, the Christ child was a central symbol of their whole community's suffering innocence (witness Southwell's The burning babe), whereas Protestants saw this as case of childish dependence.

Many of the book's themes come together in a delightful coda, which leads us through a pair of interludes written as family entertainments by the Blundell family in Lancashire in the 1660s. These were suffused with an ever-present and unproblematic family Catholicism, indicating that for this generation, after the storm, ‘Catholicism was not primarily the nostalgia-laden faith of their fathers, but the faith of their children’ (p. 198). First and last, however, these interludes were simple fun: episodes of licensed and gentle misrule, in which the children took their father's bass viol (which they were normally forbidden to touch), dressed it up as the man himself, and plucked its strings to pretend it was booming out orders to be good. It is a recurrent theme through the book. Historians can be tempted to discount reports of pious and well-behaved children as stereotypes, and to valorise unruliness and disobedience. But many children were and are immensely serious, especially in times of trial. It may be that many academics doubt this because, once upon a time, we were ourselves tediously good boys and girls. Underwood, I rather suspect, was not.