Bauer, Johannes B., Manfred Hutter, and Anneliese Felber. Lexikon der christlichen Antike. Stuttgart: Alfred Kröner Verlag, 1999. Ref. BR95 .L46 1999
Somewhat similar to Kelly’s Concise Dictionary of Early Christianity (see below) but entries tend to be more detailed and cover many topics not included by Kelly. Brief bibliographies.
Bercot, David, W. ed. Dictionary of Early Christian Beliefs: A Reference Guide to More than 700 Topics Discussed by the Early Church Fathers. Peabody, MA: Henderickson, 1998. Ref. BR66.5.D53 1998
A selection of brief quotes taken from the ten-volume Ante-Nicene Fathers but excluding those writings now regarded as "spurious, post-Nicene, or Gnostic in origin," alphabetically arranged by topic from "Abandonment of Infants" to "Zoraster, Zorastrianism." Must be used cautiously, see the "Three Mistakes to Avoid" when using dictionary on pp.xii-xiii.
Di Berardino, Angelo, ed. Encyclopedia of Ancient Christianity. 2nd ed. 3 vols. Downers Grove, IL: IVP Academic, 2014. Ref. BR66.5.D5813 2014
English translation of the next item. 30 new articles have been added to the English-language addition (for a list of these, see the "Preface to the Second English Edition," p. ix). Coverage extends to Bede in the West and John of Damascus (roughly AD 90 to 750) in the East but these limits have been exceeded for such areas as Syria, Ethiopia, Mauretania and Arabia. The first edition (Encyclopedia of the Early Church. Ref. BR66.5.D5813 1992) may still be consulted for the extensive collection of maps and illustrations at the end of vol. 2, not included in the second edition.
_____, ed. Nuovo Dizionario Patristico e di Antichita Christiane. 2nd ed. 3 vols. Marietti, 2006. Ref. BR66.5.D58 2006
Original Italian edition of the Encyclopedia of Ancient Christianity.
Esler, Philip F., ed. The Early Christian World. 2nd ed. London and New York: Routledge; Taylor & Francis Group, 2017. Ref. BR165.E17 2017
Collection of topical essays highlighting the social dimensions of the topics covered and often explicitly employing social-scientific method. Areas covered include the social, political, and intellectual context of the Mediterranean world in which Christianity was born and developed, the development of Christian communities, everyday Christian life, external (intellectual opposition, persecution) and internal (Christian dissent, heresy) aspects of early Christianity. Several essays profile significant individuals in early Christian history. New essays in the second edition cover Jewish and Christian interaction in the early centuries; ritual; the New Testament in Roman Britain; Manichaeism; Pachomius the Great and Gregory of Nyssa.
Ferguson, Everett, ed. Encyclopedia of Early Christianity. 2nd ed. 2 vols. New York & London: Garland Publishing, Inc., 1999. Ref. BR162.2.E53 1999
A revision of the well-received 1990 edition, this encyclopedia "provides a useful orientation to the major topics, the scholarly issues, and the literature through which to begin exploring an important but complex set of places, times, and people" (Eugene Teselle, review in Church History 67 (1997), p. 350-351.. Coverage extends to approximately 600 C.E. (though this is not rigidly adhered to).
Kazhdan, Alexander P., ed. Oxford Dictionary of Byzantium. 3 vols. New York; Oxford: Oxford University Press, 1991. Ref. DF521.O93 1991
According to the preface, this is the "first attempt to collect within a single work data concerning all fields of Byzantine studies." Of primary interest to Byzantinists but useful for articles on early eastern Christianity, etc. See Johnston, Recent Reference Books, p. 171 and the reviews in Byzantinische Zeitschrift, 84-85 (1991-92), pp. 512-515 and Religious Studies Review 18 (1992), pp. 271-275.
Kelly, Joseph F. The Concise Dictionary of Early Christianity. Collegeville, MN: Liturgical Press, 1992. Ref. BR95.K395 1992
Brief entries, useful primarily for quick look up basic information. Brief, general bibliographic essay on pp. 193-195 but no bibliographies with entries.
Klauser, Theodor et al, eds. Reallexikon für Antike und Christentum. Stuttgart: Hiersemann, 1950- . Ref. BR131.R4
See Jenkins, Classical Studies, p. 48f. (#144-145); Johnston, Recent Reference Books, p. 177-180. Latest volume (28) covers Poseidon--Reue. Covers classical antiquity in relation to the history of early Christianity. The first volume (Aaron-Biographie) of a series of supplemental volumes reverting to the beginning of the alphabet was published in 2002.
McGuckin, John Anthony. The Westminster Handbook to Patristic Theology. Louisville, KY: Westminster John Knox Press, 2004. Ref. BR162.3.M38 2004
Concise and introductory reference work with brief bibliographies; note the helpful "Thematic Guide to Reading the Handbook" on pp. xiii-xv.
William Smith and Henry Wace, eds. A dictionary of Christian biography, literature, sects and doctrines. 8 vols. [Whitefish, MT]: Kessinger Pub., [2005?] (originally published: London : John Murray, 1877-1887). Ref. BR95.S65 2005
An old but still useful compilation. See Kepple, Reference Works, p. 137 (BB14).