Although the Polish Reformer Johannes a Lasco was not one of the leading figures at the forefront of the European Reformation, he nonetheless had a significant place as one of the organizers of the movement. Like men such as Johannes Brenz, Martin Bucer, and Johannes Bugenhagen, a Lasco translated the theological concepts and tenets of the Reformation into actual religious practice. These men were responsible for establishing churches and defining evangelical worship. The principal focus of this work is not on the life and career of a Lasco himself, but on the Forma ac ratio that he composed. This was one of the most comprehensive of these statements of religious practice and belief during the Reformation era. Although contemporaries recognized the importance of this work, which was published in 1555, until recently it has received relatively little attention from historians.

Although the text of the Forma ac ratio was finalized in Emden and its publication completed in Frankfurt, the work was mainly composed in London. The order was a comprehensive description and justification of the administration, ceremonies, and the discipline of the foreign churches in London, which had been established by letters patent issued by Edward VI in 1550. This monograph provides one of the most detailed accounts of the circumstances that led up to the foundation of these communities and the part that a Lasco, who became the first superintendent of the congregations, played in the process. While the Forma ac ratio has been regarded as a blueprint for church formation, its compilation took place after the liturgy, confessional statement, and administrative framework for the foreign congregations had been established.

At the core of this monograph is a detailed examination over three chapters of the administration, ceremonies, and discipline of the London stranger churches. Besides giving an account of the character and nature of the religious practices and government outlined by a Lasco in the Forma ac ratio, the author demonstrates the different theological and ecclesiological influences upon the Polish Reformer. For example, the office of superintendent might be regarded as being at odds with the Reformed polity, which generally characterized these congregations; a Lasco saw the role as being one that provided leadership and oversight within the Church, through advising on doctrinal matters and maintaining discipline. As the holders of this office were also ordained ministers, they were expected to preach and perform the other duties of that position. Calvin had specifically rejected the notion of a reformed episcopate, believing there was no difference in the responsibilities of ministers and bishops. The spiritual oversight that a Lasco envisaged for this position reflected the tradition of Luther and Melanchthon, which was seen in a number of German ecclesiastical ordinances. In other respects, the conception of the ecclesiastical polity was much closer to the Genevan model. The subsequent chapters on the liturgy and the sacraments, and the exercise of ecclesiastical discipline, are similarly deftly handled and provide a thorough and clear analysis of the practices, and the religious thinking that underpinned them, within the London churches.

One of the strengths of this volume is that the Forma ac ratio is not seen in isolation or as being purely related to the religious situation in London during the early 1550s. In an opening chapter, the broader context of the Forma ac ratio is sketched out, with a survey of the emergence of church orders as confessional statements, and documents the defining of these communities. The importance and influence of the London church order is considered in the final chapter of the volume, as the congregations were forced into exile following the accession of Mary Tudor in 1553. The continuance of the religious practices developed in London is evident in the new exile congregations that were established in Emden and Frankfurt. Springer also demonstrates the significance of this church order for the communities of English exiles in Frankfurt, but in particular, in Geneva. The Forma ac ratio was, however, only one influence, as Calvinist ideas also played a part in shaping these exile communities, and this can also be seen further afield in a Lasco's efforts to reform Little Poland. The different ecclesiologies of a Lasco and Calvin came to a head in France. Jean Morély, who had been a member of the London congregation, advocated that the congregation should have a prominent role in the government of the church, which was opposed by the more restricted Genevan model that ultimately triumphed in France.

As Springer points out, it is ironic that the Forma ac ratio had relatively limited influence in England, where it had been hoped that the model and example of the stranger communities would encourage the more radical reform of the nation's church (149–50). Nonetheless, one of the more important aspects of this monograph has been to demonstrate the wider significance of the Forma ac ratio—that while it did represent a definitive blueprint and explication of the practices of the London congregations, it did influence, more broadly, religious thinking about ecclesiastical government and church building. By providing such a close and coherent examination of such an important church order in a lucid and accessible manner, the author has demonstrated clearly the different theological strands that shaped and defined religious practices in the Reformed tradition.