Study name	Comparison	Time point	Sample size T (C)	Outcome	Effect size (d)	Age T (C)	Design	Intervention type/Intervention duration
Note. Many of the publications included in the review are based on data from the same sample or parts of the same sample. In a parenthesis in the first column of the tables, after the author names, a number in a parenthesis indicates which sample or part of a sample the data are based on. The samples are labelled as follows: Boets et al. = 1; Dutch sample of dyslexia = 2; Jyväskylä sample = 3; Danish sample = 4; Snowling et al. = 5; Pennington et al. = 6; Scarborough sample = 7; Smith et al. = 8; McBride-Chang et al. = 9; Hoeft et al. = 10; Gaab et al. = 11; de Bree et al. = 13; ELDEL sample = 14; Hindson et al. = 15. BAS = British Ability Scales; Bayley MDI = Bayley Mental Developmental Index; BNT = Boston Naming Test; BPVS = British Picture Vocabulary Scale; CELF = Clinical Evaluation of Language Fundamentals; CN Rep = Children’s Test of Nonword Repetition; Comp = comprehension; DAS = Differential Ability Scales; CPM = Colored Progressive Matrices; DEAP = Diagnostic Evaluation of Articulation and Phonology; GORT = Gray Oral Reading Tests; K-BIT = Kaufman Brief Intelligence Test; m-ABC = Movement Assessment Battery for Children; M CDI = MacArthur-Bates Communicative Development Inventories; NARA = Neale Analysis of Reading Ability; NEPSY = Developmental Neuropsychological Assessment; PA = phonological awareness; PCC = percentage consonants correct; Phon Aw = phonological awareness; Phon memory = phonological memory; PPVT = Peabody Picture Vocabulary Test; RAN = rapid naming; SON-R = Snijders-Oomen nonverbal intelligence tests; vSTM = verbal short-term memory; WAIS = Wechsler Adult Intelligence Scale; WPPSI = Wechsler Preschool and Primary Scale of Intelligence; WISC = Wechsler Intelligence Scale for Children; WJ = Woodcock Johnson; WOLD = Wechsler Objective Language Dimensions; WORD = Wechsler Objective Reading Dimensions; Word ID = word identification; WRMT= Woodcock Reading Mastery Tests; YARC = York Assessment of Reading for Comprehension.
Duff et al., (2015) (14)	Trained at risk vs. controls at risk.	Posttest	67 (77)	Language comprehension	.03	6 years (6 years)	Randomized waiting list design	Reading and language intervention (RALI), phoneme awareness/decoding, and language comprehension skills
				Letter knowledge				One group 9 weeks of intervention, the other group 18 weeks of intervention alternating between 20 and 30 min group and individual daily sessions. Implemented by teaching assistants.
				Nonword reading	.24
				Phon Aw	.17
				Spelling	.40
				Word reading	−.21
					.00
Elbro & Petersen, 2004 (4)	Trained at risk vs. controls at risk	Posttest	35 (47)	Letter knowledge	.99	6:2(6:2)	Nonrandomized pre/posttest control group design	Training program written for the study, inspired by the Lundberg and the Lindamood programs. Focused on phoneme-awareness training and letter knowledge. Intervention was 30 min a day for 17 weeks, delivered by kindergarten teachers.
				Phon Aw	1.14
				RAN	−.22
	Trained at risk vs. controls not at risk	Posttest	35 (41)	Letter knowledge	.39
				Phon Aw	.24
				RAN	.06
	Trained at risk vs. controls at risk	Follow-up gain 2nd–3rd grade	35 (47)	Nonword reading	−.01
				Word reading	−.18
	Trained at risk vs. controls not at risk	Follow-up gain 2nd–3rd grade	35 (41)	Nonword reading	−.04
				Word reading	−.17
Fielding-Barnsley, & Purdie, 2003	Trained at risk vs. controls at risk	Posttest	26 (23)	Language comprehension	−.08	70.2 (70.5)	Nonrandomized pre/posttest control group design	Dialogic reading intervention where parents were asked to read to their children using the principles of dialogic reading. Five times during the 8-week intervention.
				Phon Aw
				Spelling	.23
				Word reading	1.26	1st grade
					1.09
Hindson et al., 2005 (15)	Trained at risk vs. controls at risk	Posttest	69 (17)	Letter knowledge	.12	54.6 (55.5)	Nonrandomized pre/posttest control group design	The sound foundations package based on training the children on a limited set of phonemes. The intervention was delivered by one of two teachers from research group either at home or in school. Each session 30 min, 11–17 sessions within a period of 3 months
				Ph awareness	.88
	Trained at risk vs. controls not at risk	Posttest	69 (65)	Letter knowledge	−.22
				Phon Aw	−.18
Regtvoort & van der Leij, 2007 (2)	Trained at risk vs. controls at risk	Posttest	31 (26)	Letter knowledge	.87	5:7 (5:7)	Nonrandomized pre/posttest control group design	Word building (Beck 1989). Focuses on reading instruction, letter–sound correspondence, and phonemic awareness. Children were trained by their parents, 10 min a day, 5 days a week for 14 weeks.
				Phon Aw	.48
				RAN	−.32
	Trained at risk vs. controls not at risk	Posttest	31 (16)	Letter knowledge	.84
				Phon Aw	.13
				RAN	−.19
	Trained at risk vs. controls at risk	Follow-up gain middle 1st grade to end 1st	31 (26)	RAN	−.09
				Word reading	−.16
	Trained at risk vs. controls not at risk	Follow-up gain middle 1st grade to end 1st	31 (16)	RAN	−.14
				Word reading	−.15
	Trained at risk vs. controls at risk	Follow-up gain end of 1st grade to end of 2nd	31 (26)	Nonword reading	.46
				RAN	.20
				Spelling	−.17
				Word reading	−.10
	Trained at risk vs. controls not at risk	Follow-up gain end of 1st grade to end of 2nd	31 (16)	Nonword reading	.26
				RAN	.75
				Spelling	−.58
				Word reading	.01
van Otterloo & van der Leij, 2009 (2)	Trained at risk vs. controls at risk	Posttest	30 (27)	Letter knowledge	.50	69.87 (71.13)	Posttest-only control group design	Sounding sounds and Jolly letters–a home-based prereading program with parents as tutors, 10 min a day, 5 days a week for 14 weeks.
				Phon Aw	.19
				RAN	.27
		Follow-up mid 1st grade	30 (27)	Phon Aw	.09	Middle of first grade
				Word reading	−.34
		Follow-up end 1st grade		Phon Aw	−.11	End of first grade
				Word reading	−.41