The numeration of the Psalms.

The differences between the principal versions.

The two principal ancient versions of the Old Testament, the Hebrew Masoretic and the Greek Septuagint, differ in their numeration of the book of Psalms. Both versions cover approximately the same ground, and both versions come out to 150 psalms, but they divide and combine different psalms differently to arrive at that total.

The chart below lays out the divisions of each version synoptically. The psalms in which the two versions differ as to division or combination are boldfaced. The few psalms which are numbered identically between the two systems are italicized.

Hebrew. Greek.
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9-10 9
11 10
12 11
13 12
14 13
15 14
16 15
17 16
18 17
19 18
20 19
21 20
22 21
23 22
24 23
25 24
26 25
27 26
28 27
29 28
30 29
31 30
32 31
33 32
34 33
35 34
36 35
37 36
38 37
39 38
40 39
41 40
42 41
43 42
44 43
45 44
46 45
47 46
48 47
49 48
50 49
51 50
 
Hebrew. Greek.
52 51
53 52
54 53
55 54
56 55
57 56
58 57
59 58
60 59
61 60
62 61
63 62
64 63
65 64
66 65
67 66
68 67
69 68
70 69
71 70
72 71
73 72
74 73
75 74
76 75
77 76
78 77
79 78
80 79
81 80
82 81
83 82
84 83
85 84
86 85
87 86
88 87
89 88
90 89
91 90
92 91
93 92
94 93
95 94
96 95
97 96
98 97
99 98
100 99
101 100
 
Hebrew. Greek.
102 101
103 102
104 103
105 104
106 105
107 106
108 107
109 108
110 109
111 110
112 111
113 112
114-115 113
116 114-115
   
117 116
118 117
119 118
120 119
121 120
122 121
123 122
124 123
125 124
126 125
127 126
128 127
129 128
130 129
131 130
132 131
133 132
134 133
135 134
136 135
137 136
138 137
139 138
140 139
141 140
142 141
143 142
144 143
145 144
146 145
147 146-147
   
148 148
149 149
150 150

The Vulgate follows the Greek numeration system.

The numbering of the psalms, unlike the chapter and verse divisions of the rest of the Bible, is ancient. Already in Acts 13.33 we find numerical reference to the book of Psalms:

...οτι ταυτην ο θεος εκπεπληρωκεν τοις τεκνοις αυτων ημιν αναστησας Ιησουν, ως και εν τω ψαλμω γεγραπται τω δευτερω·* Υιος μου ει συ· εγω σημερον γεγεννηκα σε.

* Most manuscripts by far have δευτερω, but D, supported by some Old Latin manuscripts and church fathers, has πρωτω. It appears that Ƿ45 omits numeration entirely and has only the plural τοις ψαλμοις. Psalm 2.7 is the intended referent.

...that God has fulfilled this [promise] to us their children in having resurrected Jesus, as it is also written in the second psalm: You are my son; today I have begotten you.

As I understand it (though I have no references handy for it), later rabbinical sources such as the Talmud sometimes combine the first with the second psalm; hence the western variant in which Psalm 2.7 is said to come from the first (πρωτω) psalm instead of the second.