Following are depictions and portraits of boys and girls from the Renaissance. Because the goal of this survey is to provide useful information on a realistic view of children's clothing, I have avoided most allegorical or overly anachronistically-dressed children. I've also included links to extant clothing worn by pre-17th century children.

Take a look at Children's Portraits for more 16th-19th century examples. More discussion on this topic at the Garb The Child LiveJournal Community. For 17th century examples, see Costume Focus 1660-1715: Children Research Gallery.

• Portrait of Urschelin Burgkmair by Hans Burgkmair, c. 1500
• The Wealthy Man by Jean Bourdichon, from Les Quatre États de la Société, c. 1500-1510
• Hans Holbein's sons Hans and Ambrosius in a panel by Hans Holbein the Elder, 1504
• Triptych of Jan Des Trompes by Gerard David, 1505
  The side panels depict the family of the donor; this detail provides a clearer view of his first wife and their daughters. The rear of the wings includes a portrait of the donor's second wife and their daughter.
• Portrait of a Young Girl by Albrecht Dürer, 1507
• St. Anne Altarpiece by Quentin Massys, 1507-08
  Several boys depicted in contemporary dress. Note especially the children of Mary Cleophas; baby Joseph seems to be wearing a sort of bib, embroidered with a cross.
• Triptych with the Holy Kinship and the Trinity with members of the Merode-Petershem family, southern Netherlands, c. 1510
• A small boy with his family in April in a book of hours, c. 1510-1560
• January (fol. 2v) and April (fol. 5v) in the Da Costa Hours (PML M.399), c. 1515
• Portrait of a Girl by Albrecht Dürer, 1515
• Signboard for the Schoolmaster Myconius by Ambrosius Holbein, 1516
• Boy with Blonde Hair and Boy with Brown Hair by Ambrosius Holbein
• A Prince of Saxony by Lucas Cranach the Elder, 1517
• A Princess of Saxony by Lucas Cranach the Elder, 1517
• Conrad Rehlinger and his Children by Bernhard Strigel, 1517
• Triptych of the Adoration of the Magi by Jacob Cornelisz van Oostnanen, 1517
• A Young Girl of Cologne by Albrecht Dürer, 1520
• Madeleine of France by Jean Clouet, c. 1520
• January (fol. 18v) and April (fol. 21v), The Golf Book (British Library Add. 24098), c. 1520-1530; there are also images of boys playing games on most pages of this book of hours
• The Dauphin François, Son of François I by Jean Clouet, ca. 1523
• A Family Group by Bernardino Licinio, 1524
• Child's caftan, second quarter of the 16th century
• Two pairs of farmers with children at a covered table by Pieter Brueghel the Elder, c. 1525-1569
• The children of Christian II of Denmark by Jan Gossaert, 1526
• The Darmstadt Madonna by Hans Holbein the Younger, 1526 and after 1528
• Rural scene by Marten van Cleve, 1527
• The Artist's Family by Hans Holbein the Younger, 1528
• Portrait of a Man with Three Sons by Barthel Bruyn, 1530
• Family Portrait by Maerten van Heemskerck, c. 1530
• January in the Hennessey Book of Hours (Bibl. Royale Albert Ier MS H, 158, fol. 1v), c. 1530-1540
• Young Girl with Astronomic Instrument by Jan Gossaert
• Portrait of Arrigo Licinio and his Family by Benardino Licinio, 1535 (detail)
• Peasants Merrymaking at a Village Kermesse by Hans van Wechlen, c. 1537
• Edward, Prince of Wales by Hans Holbein the Younger, 1539
• Portrait of a Young Girl, Lucas Cranach the Elder, 1540
• Three men and a little girl, c. 1540
• Henry Brandon by Hans Holbein the Younger, 1541
• Charles Brandon by Hans Holbein the Younger, 1541
• Edward, Prince of Wales, with Monkey by Hans Holbein the Younger, 1541-1542
• Bia by Agnolo Bronzino, before 1542
• Clarissa Strozzi by Titian, 1542
• Edward, Prince of Wales by Hans Holbein the Younger, 1543
• Portrait of a boy, c. 1545
• Portrait of a girl by Jakob Seisenegger, c. 1545-1550
• Count Alborghetti of Bergamo and his son by Giovanni Battista Moroni, c. 1545-1550
• Red-headed Youth Holding a Drawing by Giovanni Francesco Caroto, before 1546
• Giovanni della Volta with his Wife and Children by Lorenzo Lotto, 1547
• Giovanni de'Medici by Agnolo Bronzino, 1549
• The Shelley sons, 1549
• Boy's embroidered shirt, c. 1550
• Infant's knitted sock, vest and mitten (mid-16th century?). Baby clothes knitted in soft white wool; the mitten has a contrasting band, probably of naturally black sheep's wool. Another photo here.
• Knitted and felted cap with a decoratively slashed brim; 16th century
• Drawings of the children in the French royal family: Hercule-François, unidentified child (possibly Henri III), François II (c. 1550s), another of François II (c. 1560), Marguerite of Valois, and Charles IX
• Boy's leather jerkin, c. 1550-1600
• Infant’s coif, c. 1550-1600
• Eleonora of Toledo with her son Giovanni de' Medici by Agnolo Bronzino, 1550
• Don Garcia de' Medici by Agnolo Bronzino, 1550
• Francesco I de' Medici by Agnolo Bronzino, 1551
• Maria de' Medici by Agnolo Bronzino, 1551
• Livia da Porto Thiene and her daughter Porzia and Iseppo da Porto and his son Adriano by Paolo Veronese, c. 1551
• The dauphin (later François II) by Lonard Limosin, 1553
• Marguerite de Valois by François Clouet, c. 1555
• François II (by François Clouet?)
• Hercule-François, Duke of Alençon, c. 1556-1558
• Much of the work of Pieter Bruegel the Elder features children, including Children's Games (1559), Peasant Wedding (1568), Peasant Dance (1568).
• The Pelham sons and daughters, c. 1559
• Giuseppe Gualdo and sons by Giovanni Antonio Fasolo, c. 1560
• Peasants by the Hearth by Pieter Aertsen, 1560s
• Boys at various ages in the early 16th century, from the Schwartz Trachtenbuch, 1561. (Note that the BNF illustrations are in color, but are from a 1704 copy of the manuscript.) There is some contrast between the childhood clothing of Matthaus (who grew up in the early 16th century) and his son Conrad (who grew up in the 1540s). Thanks to Sophia Kress for her help with these manuscripts!
  Matthaus as a sickly three-year-old (see also BNF Allemand 211, fol. 9)
  Matthaus learns the alphabet at the age of five years and four months (see also BNF Allemand 211, fol. 4)
  Nine-year-old Matthaus has run away, and makes a living begging for bread and working for cowherds (see also BNF Allemand 211, p. 13)
  Matthaus plays in the street at the age of eleven years and 8 months (see also BNF Allemand 211, fol. 7v)
  At the age of 12, Matthaus goes through a phase of wanting to be a monk, and holds Mass in his bedroom with his own miniature altar (see also BNF Allemand 211, fol. 9)
  Conrad, aged 1 to 3 years (one with a walker, and one wearing a pudding-cap and apparently being held up with leading strings?)
  Conrad, at age eight and a half, playing various games in the street
  Conrad, age ten, plays in the snow
• Portrait of Juana of Austria with a young girl, 1561
• Lady Katherine Grey and her son Lord Edward Beauchamp, c. 1561-1563
• Pierre de Moucheron, Merchant of Middelburg and Antwerp, and his family, 1563
• Henry Stuart and his brother Charles Stuart by Hans Eworth, 1563
• A boy with a birdcage by Abraham Bloemaert, 1566
• Fête at Bermondsey by Joris Hoefnagel, 1569
• Charles IX by François Clouet, 1570
• Detail from a portrait of a woman and two children by Giovanni Battista Moroni, 1570
• Portrait of a Family with Arms of Mosto and Costanzo (Detail) by Tintoretto, 1570s
• A little girl with a basket of cherries, 1570s
• Infantas Isabel Clara Eugenia and Catalina Micaela by Alonso Sanchez Coello, c. 1571
• Swaddling Band, Italy, c. 1575-1600; a later swaddling band, Italy, c. 1600-1625; a christening outfit, Belgian lace assembled in England, c. 1650-1700. Also, a 17th century tailclout at the National Museum of Childhood.
• Foemina Mediocris conditionis in Silesia (Commoner from Silesia) from Habitus praecipuorum populorum by Hans Weigel, 1577
• Antonius Anselmus, His Wife and Their Children by Marten de Vos, 1577
• Arabella Stuart, 1577
• Sketch by Adam Elsheimer, c. 1578-1610
• A young boy by Jacob Willemsz Delff I, 1581
• Portrait of a girl of the Walenburg family by Hans von Aachen, 1582
• Otto Venius painting, surrounded by his family, 1584
• Oliver Pelham, 1584
• Two Young Men by Crispin van den Broeck, before 1590
• Miniatures of unknown children by Isaac Oliver, 1590: a four-year-old girl holding an apple, a five-year-old girl holding a carnation, and an infant
• Prince Karel of Arenberg and his family by Frans Pourbus de Jonge, c. 1593
• Frances Walsingham, countess of Essex, and her son Robert, later the third Earl of Essex by Robert Peake the Elder, 1594
• Unknown lady with two children, 1595
• Boy servants in the Album Amicorum of a German Soldier, 1595, including: Donzela Senese, Sposa Senese, Marchese Napolitana, and Donzela Senese
• Barbara Gamage, Lady Sidney, later Countess of Leicester, with two sons and four daughters, c. 1596
• Anne, Lady Pope with her children by Marcus Gheeraerts the Younger, 1596
• Philip of Savoy, Prince of Piedmont, 16th century
• Thomas Stewkley, 1601
• Double portrait of a brother and sister by Cornelis Ketel